CLIMATE SCIENCE
Assumptions, policy implications, and the scientific method

Judith Curry, John Christy, Michael Mann and Roger Pielke Jr

The Global Warming Policy Foundation
GWPF Report 24

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CLIMATE SCIENCE

Assumptions, policy implications, and the scientific method

Judith Curry, John Christy, Michael Mann and Roger Pielke Jr

ISBN 978-0-9931189-5-1© Copyright 2017 The Global Warming Policy Foundation

Contents
About this reportvi

1

Testimony of Professor Judith Curry
Major points
Introduction
Scientific method for complex environmental systems
Complexity
Assessment of climate models
How scientists fool themselves
Disagreement and reasoning about climate uncertainty
Conclusion
Notes

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15
17

2

Testimony of Professor John Christy
Summary
Introduction
Applying the scientific method to climate models from the IPCC AR5
Observational data used to test climate models
Testing the claim: applying the scientific method
The IPCC AR5 (2013) displayed a similar result: the models failed
A simple statistical model that passed the same ‘scientific method’ test
Red teams needed because consensus science is not science
In summary
Notes

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29
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32

3

Testimony of Professor Michael Mann
Biography of Michael E. Mann
Notes

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43
44

4

Testimony of Professor Roger Pielke Jr
Take-home points
My recent experiences where science meets politics
Lessons of my experience
Improving the state of scientific integrity in climate science
To avoid any confusion: my views on climate science and policy
Biography of Roger Pielke Jr.
Appendix A: 2016 op-ed on my experiences in climate research
Notes

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46
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57

About this report
This report publishes testimony given by four prominent climate scientists to a hearing of the Committee on Science, Space and Technology of the US House of Representatives on 29 March 2017. Minor stylistic changes have been made to the text as
originally presented by the witnesses.

vi

1 Testimony of Professor Judith Curry
Major points• Scientific progress is driven by the creative tension spurred by disagreement,
uncertainty and ignorance.
• Progress in understanding the climate system is being hampered by an institutionalized effort to stifle this creative tension, in the name of a ‘consensus’ thathumans have caused recent climate change.
• Motivated by the mandate from the United Nations Framework Convention on
Climate Change (the UNFCCC), the climate community has prematurely elevated a scientific hypothesis on human-caused climate change to a ruling theory through claims of a consensus.
• Premature theories enforced by an explicit consensus-building process harmscientific progress because of the questions that don’t get asked and the investigations that aren’t undertaken. As a result, we lack the kinds of information tomore broadly understand climate variability and societal vulnerabilities.
• Challenges to climate research have been exacerbated by:– unreasonable expectations from policy makers– scientists who are playing power politics with their expertise and trying tosilence scientific disagreement through denigrating scientists who do notagree with them– professional societies that oversee peer review in professional journals writing policy statements endorsing the consensus and advocating for specific policies.
• Policymakers bear the responsibility of the mandate that they give to panelsof scientific experts. The UNFCCC framed the climate change problem too narrowly and demanded of the IPCC too much precision – where complexity, chaos,disagreement and the level of current understanding resists such precision.
• A more disciplined logic is needed in the climate change assessment processthat identifies the most important uncertainties and introduces a more objective assessment of confidence levels.
• Expert panels with diverse perspectives can handle controversies and uncertainties by assessing what we know, what we don’t know, and where the major
areas of disagreement and uncertainties lie.

1Introduction
I thank the Chairman and the Committee for the opportunity to offer testimony today on ‘Scientific Method as it Relates to Climate Change’. I am Professor Emeritus of
the School of Earth and Atmospheric Sciences at the Georgia Institute of Technology.
I have devoted four decades to conducting research on a variety of topics related
to weather and climate. In recent years my focus has been on uncertainty and theinterface between climate science and policy. As President of Climate Forecast Applications Network LLC, I have been working with decision makers to use weather andclimate information to reduce vulnerability to extreme weather and climate events.
I am increasingly concerned that both the climate change problem and its solution have been vastly oversimplified. The result of this simplified framing of a complex, wicked problem is that we lack the kinds of information to more broadly understand climate variability and societal vulnerabilities.
Motivated by the mandate from the United Nations Framework Convention on
Climate Change (UNFCCC) to address dangerous human-caused climate change, theclimate community has worked for more than 20 years to establish a scientific consensus on human-caused climate change, which has prematurely elevated a scientifichypothesis to a ruling theory. Premature theories enforced by an explicit consensusbuilding process harm scientific progress because of the questions that don’t get
asked and the investigations that aren’t undertaken.
Challenges to climate research have been exacerbated by:• expectations from policy makers• scientists who are playing power politics with their expertise and trying to silence scientific disagreement through denigrating scientists who do not agreewith them• professional societies (that oversee the peer review in professional journals)
who are writing policy statements endorsing the consensus and advocating forspecific policies.
Motivated by these concerns, my testimony focuses on the following issues of central
relevance to the issues of climate science and the scientific method:• the scientific method for complex environmental systems• how scientists fool themselves• disagreement and reasoning about climate uncertainty• the interface between climate science and policy.

Scientific method for complex environmental systems
My perspective on the scientific method is based on four decades as a scientist andextensive readings on the philosophy and sociology of science. Over the past seven2years, I have been exploring these issues as they relate to climate science in a seriesof blog posts1 and several publications.2 My perspective is summarized below.
Science is a process for understanding how nature works. The scientific process
can be summarized as: ask a question or pose a hypothesis, set up an objective test or
experiment, and make a scientific argument – and then repeat. A scientific argument
uses logic to combine assumptions and evidence. Science is often mis characterized
as the assembly and organization of data and as a collection of facts on which scientists agree. Science is correctly characterized as a process in which we keep exploringnew ideas and changing our understanding of the world, to find new representationsof the world that better explain what is observed. Part of science is to do calculations
and to make predictions, but another part of science is to ask deep questions about
how nature works.
‘Scientifically proven’ is a contradiction in terms – science does not prove anything. Scientists have a vision of reality that is the best they have found so far, andthere may be substantial disagreement among individual scientists. Science works
just fine when there is more than one hypothesis to explain something – in fact, disagreement spurs scientific progress through creative tension and efforts to resolve
the disagreement. Science is driven by uncertainty, disagreement and ignorance –the best scientists actively cultivate doubt. Scientists do not concentrate on what
they know, but rather on what they don’t know. Science is an ongoing process ofrevision that may be incremental, and occur in fits and starts or through an unexpected breakthrough. Scientists tackle ignorance in formulating their research approach through challenging assumptions and presuppositions, curiosity, imagination, identifying connections with other research, and revisiting apparently settled
questions.
How do we evaluate scientific theories, which are collections of hypotheses? All
theories are underdetermined by data. Theories are evaluated based on independent
corroboration, effectiveness in explaining phenomena and making predictions. Aspects of science that are reasonably settled are reliably used as assumptions for otherscientific investigations and often enter into the realm of engineering.
What is the status of climate science as it relates to the nature and causes of variations on timescales from decades to centuries? The foundation of climate science
rests on fundamental laws such as Newton’s laws of motion, Planck’s law and the
Stefan Boltzmann law, the first and second laws of thermodynamics, ideal gas laws,
gravitation, and conservation of mass and energy. There are numerous theories ofcomplex processes (collections of hypotheses) that contribute to our understandingof climate science, including the theory of rotating fluids, the theory of boundary layers, the theory of gaseous infrared spectroscopy and radiative transfer. These theories
are widely accepted.
The meta-theory of greenhouse warming of the climate system incorporates many3

hypotheses and theories about how components of the climate system work. It is anempirical fact that the Earth’s climate has warmed overall for at least the past century. However, we do not know how much humans have contributed to this warming
and there is disagreement among scientists as to whether human-caused emissionsof greenhouse gases are the dominant cause of recent warming, relative to naturalcauses.

Complexity
Scientific arguments in physics, chemistry and cell biology are typically based on controlled laboratory experiments, where explanation and prediction can be based ona few variables. There are elements of climate science that can be addressed using
these methods, notably in atmospheric chemistry and the physics and chemistry ofaerosol and cloud particles.
However, scientific investigations of the dynamics of the entire climate systemhave more in common with systems biology and economics than with laboratory
physics and chemistry, owing to the complexity of the systems under investigationand the inability to conduct controlled experiments. Complexity of the climate system arises from chaotic behavior and the nonlinearity of the equations for motions in
the atmosphere and ocean, high dimensionality of the system (many different variables, varying in three dimensions and with time), and the linking of multiple subsystems (e.g. atmosphere, oceans, land surface, glacier ice).
The aggregate properties and changes of complex systems cannot be determinedfrom sum of the individual components, owing to interactions among the components and the different scales of organization within the system. Complex systems
are studied using information theory and computer simulation models (e.g. global
climate models.) While some of the equations in climate models are based on thelaws of physics, many key processes in the model are only approximated and are notdirectly related to physical laws.
Global climate models are used by scientists to represent aspects of climate thatare difficult to observe, experiment with theories in a new way by enabling hitherto
infeasible calculations, understand a system of equations that would otherwise be
impenetrable, and explore the system to identify unexpected outcomes. As such,global climate models are an important element of climate research. For models of acomplex system, the notion of a correct or incorrect model is not well defined. The
relevant issue is whether the model ‘works’ and is fit for its intended purpose.

Assessment of climate models
In a recent report entitled Climate Models for Laymen,3 I described how climate models
are useful tools for conducting scientific research to understand the climate system.
4However, I argued that current global climate models are not fit for the purpose of
attributing the causes of recent warming or for predicting global or regional climatechange on timescales of decades to centuries, with any high level of confidence. Concerns about the utility of climate models include:• Predictions of the impact of increasing CO2 on climate cannot be rigorously
evaluated for order of a century.
• Failure to provide a consistent explanation of the early 20th century warming
and the mid-century cooling.
• Inability to simulate the magnitude and phasing of large-scale ocean oscillations on decadal to century timescales• Insufficient exploration of climate model uncertainties.
• Extremely large number of unconstrained choices in terms of selecting model
parameters and parameterizations.
• Evaluation of climate models against the same observations used for model
tuning.
• Fundamental lack of predictability in a complex nonlinear system.

How scientists fool themselves
Prior to 2010, I accepted and supported the consensus conclusions from the assessment reports published by the Intergovernmental Panel on Climate Change (IPCC) –I felt that this was the responsible thing to do. However, following the revelations of
Climategate,4 I realized that I had fallen victim to ‘groupthink’ – a pattern of thoughtcharacterized by conformity to group values and the manufacture of consensus that
results in self-deception. I undertook an investigation into the ways that scientists
can fool themselves, by examining deceptions from other fields of science and reading analyses from the perspectives of psychology and the philosophy and sociology
of science. Below are my reflections on how climate scientists can fool themselves,
and what they can do about it.
Cognitive biases
Because of the complexity of the climate problem, scientists use different mental
models for evaluating the interconnected evidence. Biases can abound when reasoning and making judgments about such a complex problem. Bias can occur by excessive reliance on a particular piece of evidence, the presence of cognitive biases inreasoning shortcuts, failure to account for indeterminacy and ignorance, and logicalfallacies and errors, including circular reasoning.
Cognitive biases relate to self-deception. Cognitive biases of particular relevanceto the science of climate change include:5• confirmation bias : the tendency to search for or interpret information in a waythat confirms one’s preconceptions• self-serving bias : a tendency for people to evaluate information in a way that isbeneficial to their interests• belief bias : evaluating the logical strength of an argument based on belief inthe truth or falsity of the conclusion• framing : using a narrow approach that pre-ordains the conclusion• overconfidence : unjustified, excessive belief• illusory correlations : false identification of relationships with rare or novel occurrences
A recent article by statistician Regina Nuzzo in Nature summarizes the problem:
This is the big problem in science that no one is talking about: even an honest
person is a master of self-deception. In today’s environment, our talent for jumping to conclusions makes it all too easy to find false patterns in randomness, toignore alternative explanations for a result or to accept ‘reasonable’ outcomes
without question – that is, to ceaselessly lead ourselves astray without realizing
it.5

Simply, scientists are human and subject to biases. Further, they have personal andprofessional stakes in the outcomes of research – their professional reputation andfunding is on the line. Assuming that individual scientists have a diversity of perspectives and different biases, then the checks and balances in the scientific processincluding peer review will eventually see through the biases of individual scientists.
However, when biases become entrenched in the institutions that support science –the professional societies, scientific journals, universities and funding agencies – thenthat subfield of science may be led astray for decades and make little progress.
Premature theories and manufactured consensus
A scientific argument can evolve prematurely into a ruling theory if cultural forces are
sufficiently strong and aligned in the same direction. Science policy expert Daniel
Sarewitz describes the process:
Like a magnetic field that pulls iron filings into alignment, a powerful cultural belief is aligning multiple sources of scientific bias in the same direction. The belief
is that progress in science means the continual production of positive findings.
All involved benefit from positive results, and from the appearance of progress.
Scientists are rewarded both intellectually and professionally, science administrators are empowered and the public desire for a better world is answered. 6

I have argued that cognitive biases in the context of the IPCC’s consensus-building
process surrounding human-caused climate change have resulted in the consensus
6becoming increasingly confirmed in a self-reinforcing way, to the detriment of the scientific process.7 Princeton philosopher Thomas Kelly provides some general insights
into the sources of confirmation bias and belief polarization that are relevant to theclimate change consensus.8 Kelly argues that belief held at earlier times can skew thetotal evidence that is available at later times, via characteristic biasing mechanisms, ina direction that is favorable to the initial belief. All else being equal, individuals tend
to be significantly better at detecting fallacies in an argument for a conclusion thatthey disbelieve, than when the same fallacy occurs in an argument for a conclusionthat they believe. Of particular relevance to the IPCC’s consensus on human-caused
climate change:
As more and more peers weigh in on a given issue, the proportion of the total
evidence which consists of higher order psychological evidence [of what otherpeople believe] increases, and the proportion of the total evidence which consists of first order evidence decreases. . . At some point, when the number of peers
grows large enough, the higher order psychological evidence will swamp thefirst order evidence into virtual insignificance. 9

So what are the implications of Kelly’s arguments for the IPCC’s consensus on humancaused climate change? Cognitive biases in the context of an institutionalized consensus building process have arguably resulted in the consensus becoming increasingly confirmed in a self-reinforcing way. An extended group of scientists derive theirconfidence in the consensus in a second-hand manner from the institutional authority of the IPCC and the emphatic nature in which the consensus is portrayed. This ‘invisible hand’ marginalizes skeptical perspectives and is operating to the substantial
detriment of climate science, as well as biasing policies that are informed by climate
science.
Premature theories enforced by an explicit consensus building process harm scientific progress because of the questions that don’t get asked and the investigations
that aren’t undertaken. Overconfident assertions take away the motivation for scientists to challenge the consensus, particularly when they can expect to be called a ‘denier’ for their efforts and see their chances diminish for professional recognition andresearch funding. As a result of the enforced consensus, there is little independent
thought that seeks to advance fundamental understanding or develop an independent aggregate understanding of how the climate system works.
When a field of science becomes entangled with politics and public policy debates – such as climate science – the stakes for diverging from the consensus point ofview become much higher. Rather than encouraging scientific debate, there are attempts by scientists, the media and politicians to end debate by insisting that a large
majority of scientists support a consensus, referring to those that disagree as ‘deniers’.
Sound theory does not need to demonize its opponents; rather these are the tactics
of elevating a premature theory to dogma and enforcing it for political purposes.
7Overcoming bias
A scientist’s job is to continually challenge his/her own biases and ask ‘How could I
be wrong?’ Playing ‘devil’s advocate’ helps a scientist examine how their conclusions
might be misguided and how they might be wrong. Overcoming one’s own biases isdifficult; an external devil’s advocate can play a useful role in questioning and criticizing the logic of the argument.
T.C. Chamberlain’s method of ‘multiple working hypotheses’ 10 is a strategy thatbrings into view every rational explanation of the phenomena. The value of multiple
working hypotheses lies largely in its suggestiveness of lines of inquiry that mightotherwise be overlooked. More formal methods include ‘Red team’ and ‘Team B’approaches that provide competitive analyses to challenge the dominant ones. I
have participated in two interesting experiments along these lines for climate science, which are described below.
In 2014, the American Physical Society (APS) held a workshop to consider its statement on climate change. A committee of eminent physicists, each with no particular expertise in climate science or an apparent dog in the public debate, selected six
climate scientists with diverse perspectives (Isaac Held, Ben Santer, William Collins,
Judith Curry, Richard Lindzen, John Christy) to address specific questions preparedby the committee that were related to the IPCC 5th Assessment Report. The APS produced a complete transcript of the workshop. 11 This transcript is a remarkable document – it provides, in my opinion, the most accurate portrayal of the scientific debates
surrounding climate change.
Organized under the auspices of the Dutch Ministry of Infrastructure and the Environment, Climate Dialogue12 offered a blog platform for discussions between scientists on important climate topics that are of interest to both fellow scientists andthe general public. The goal was to explore the full range of views that scientists haveon the selected issue. Each discussion was initiated by a short introduction writtenby the editorial staff, followed by guest essays by two or more invited scientists. The
scientists reacted to each other’s essays and to questions posed by the editorial staff.
The public (including other climate scientists) could comment on a separate thread.
After the online discussion, Climate Dialogue editors wrote a summary, describing
the areas of agreement and disagreement between the discussants. I participated in
the inaugural dialogue on Arctic sea ice, and there were a total of six dialogues before
the effort was terminated. Each of these dialogues is a testament to the importanceof this kind of scientific dialogue and debate in terms illuminating and clarifying thescientific issues and uncertainties.
Beyond overcoming bias, the dialectical nature of science can play an importantrole in solving problems of societal relevance. When scientific input is sought on asocially relevant issue, we need to acknowledge that there are competing hypotheses and theories that are of practical consequence. Societal problem solving would
8benefit greatly from forums that bring together the proponents of these competing
inquiries for debate and joint problem solving.

Disagreement and reasoning about climate uncertainty
During my investigation of arguments and evidence being used to support the IPCC
statement on the causes of recent climate change, it became apparent to me that
there were rational reasons for disagreement about many aspects of these arguments.
I concluded that reasoning about a complex system with many uncertainties is not
at all straightforward. My investigations on this topic included reading about argumentation and disagreement from the perspectives of philosophy and law, as well as
logical inference and network theory. I published two articles on these topics. 13,14 My
reflections on disagreement, uncertainty and reasoning about the complex climate
problem are summarized below.
Disagreement
Science proceeds just fine with indefinite conclusions, disagreement and multiple hypotheses. In fact, science works best under the creative tension of competing hypotheses. Disagreement among scientists and support for rival hypotheses can arise
from:• insufficient and inadequate observational evidence• disagreement about the value of different classes of evidence (e.g. paleoclimate
reconstructions, global climate models)• disagreement about the appropriate logical framework for linking and assessing the evidence• overconfidence and differing assessments of areas of ambiguity and ignorance• belief polarization as a result of cultural pressures and the politicization of thescience.
In the context of disagreement, it is important to distinguish between disbelief – believing an argument is false – and non-belief – believing that the argument is not true.
Disbelief is actually a case of belief, whereas non-belief is a state of suspended judgment of neither believing the argument true nor believing it false. A failure to makethis distinction was the recent media coverage of statements made by EPA administrator Scott Pruitt:
I think that measuring with precision human activity on the climate is something
very challenging to do and there’s tremendous disagreement about the degreeof impact, so no, I would not agree that it’s a primary contributor to the global
warming that we see. But we don’t know that yet. We need to continue thedebate and continue the review and the analysis. 15

9The media characterized this statement as ‘EPA head Scott Pruitt denies that carbon
dioxide causes global warming’.16 Pruitt’s statement was incorrectly characterized asa statement of disbelief, when it was clearly a statement of non-belief.
Reasoning about climate uncertainty
Reasoning about a complex system with many uncertainties is not at all straightforward. The general reasoning underlying the IPCC’s arguments for human-caused climate change is described by Oreskes as a ‘consilience of evidence’ argument, which
consists of independent lines of evidence that are explained by the same theoreticalaccount.17 Oreskes draws an analogy for the consilience of evidence approach withwhat happens in a legal case. Continuing with the legal analogy, legal scholar James
Johnston18 characterized the IPCC’s arguments as a legal brief, designed to persuade,in contrast to a legal memo that is intended to objectively assess both sides. Alongthe lines of a legal memo, the consilience of evidence argument is not convincing
unless it includes parallel evidence-based analyses for competing hypotheses. Anyevidence-based argument that is more inclined to admit one type of evidence or argument rather than another tends to be biased. Multiple lines of evidence that produce a high confidence level for each of two opposing arguments is referred to as the‘ambiguity of competing certainties’. If uncertainty and ignorance are acknowledged
adequately, then the competing certainties disappear. Disagreement and clarification of uncertainties then become the basis for focusing research in a certain area,and so moves the science forward.
The complexity of the climate system makes the concept of ‘consilience failure’
rather challenging. If one of the lines of evidence turns out to be flawed, then how
does this influence the overall argument? The ‘doesn’t matter’ versus ‘death knell’interpretations can be explained by the use of two different logics represented bythe ‘jigsaw puzzle analogy’19 and the ‘house of cards analogy.’ 20 Consider a partiallycompleted jigsaw puzzle, with many pieces in place, some pieces tentatively in place,and some missing pieces. Default reasoning allows you to infer the whole picturefrom an incomplete puzzle if there is not another picture that is consistent with the
puzzle in its current state. Under a monotonic logic, adding new pieces and locking
existing pieces into place increases what is known about the picture. For a climate
scientist having a complex mental model of interconnected evidence and processes
represented by the jigsaw puzzle, the evidence in the North report 21 critical of thepaleo-temperature reconstructions (the so-called ‘Hockey Stick’) merely jiggled loose
a few puzzle pieces but didn’t change the overall picture. Skeptics, lacking the same
puzzle frame but focused on the specific conclusions of the North report, viewed theevidence as collapsing the house of cards and justifying major belief revision on thesubject. Which frame is ‘correct’? Well, both are overly simplistic heuristics used in
the absence of formal logical arguments.
10

The ways of combining evidence and the associated uncertainties and logics becomes critical in determining how one would even go about falsifying the theory or
inferring anything about the theory from comparison of model predictions and observations. I have found that most disagreement on topics related to climate change
is associated with different mental models for assessing and combining evidence tomake inferences. A more disciplined logic is needed to assess the relative merits ofthe different arguments through identifying the most important uncertainties andintroducing a more objective assessment of confidence levels.
In ‘Reasoning about climate uncertainty’, 22 I argued that a useful approach would
be the development of hierarchical logical hypothesis models that provide a structure for assembling the evidence and arguments in support of the main hypotheses
or propositions. A logical hypothesis hierarchy (or tree) links the root hypothesis tolower level evidence and hypotheses. While developing a logical hypothesis tree issomewhat subjective and involves expert judgments, the evidential judgments are
made at a lower level in the logical hierarchy. Essential judgments and opinions relating to the evidence and the arguments linking the evidence are thus made explicit,
lending structure and transparency to the assessment. To the extent that the logicalhypothesis hierarchy decomposes arguments and evidence to the most elementary
propositions, the sources of disagreement are easily illuminated and potentially minimized.
An issue of central importance for the use of scientific research in policy making is
uncertainty management and elucidation of the elements of uncertainty. My paper‘Reasoning about climate uncertainty’ describes several such approaches that comprehensively describe the pedigree and quality of the relevant data sets and methods and characterize uncertainty in a manner that covers the range from complete
numerical formalization of probabilities to ignorance, and includes the possibility ofunspecified but surprising events. 23
The interface between climate science and policy
I first became caught up in the political debate about climate change following publication of our paper in 2005 relating hurricane intensity with global warming. 24 The
uncanny timing of publication of this paper was three weeks after Hurricane Katrina
devastated New Orleans. While global warming was mentioned only obliquely inthe paper, the press focused on the global warming angle and a media and political furore followed. My reflections on this were published in a paper entitled ‘Mixing
politics and science in testing the hypothesis that greenhouse warming is causing a
global increase in hurricane intensity’. 25 In recent years, I have continued to investigate the interface between climate science and policy, and have become increasingly
concerned about its dysfunction.
11

In the 1990s, the world’s nations embarked on a path to prevent dangerous anthropogenic climate change by stabilization of the concentrations of atmosphericgreenhouse gases, which was codified by the 1992 UN Framework Convention on Climate Change (UNFCCC) treaty.26 This objective has led to a focus on identifying human influences on climate, dangerous environmental and socio-economic impactsof climate change, and stabilization of CO 2 concentrations in the atmosphere. The
IPCC has become conflicted by its makeup and its mandate from the UN – to focus
on a change of climate that is attributed to human activity. If the IPCC found thatclimate change was not being affected by human alteration of the atmosphere orthat it is not ‘dangerous,’ the UNFCCC would not need it to exist. Findings of ‘dangerous human-caused climate change’ seem inevitable with this framing of the climatechange problem and the mandate from policymakers.
In the early 1990s there was belief in the feasibility of reducing uncertainties in climate science and climate models, and a consensus-seeking approach was formalized
by the IPCC. Global climate models were elevated to a central role through investigations of climate change impacts and applications. Very substantial investments havebeen made in further developing climate models, with the expectation that thesemodels will provide actionable information for policy makers.
The hope, and the potential, of climate models for providing actionable information for policymakers have not been realized. With the failure of climate models to
reduce uncertainty about the sensitivity of the climate system to CO 2 and the failure
to accurately simulate decadal and regional climate variability, 27 we have arguably
reached the point of diminishing returns from this particular path of climate modeling – not just for decision support but also for scientific understanding of the climate
system. The climate modeling community, the funding agencies and policy makers
have locked themselves into a single climate modeling framework that has been very
expensive in terms of funding and personnel.
An unintended consequence of this strategy is that there have been very few resources left over for true climate model innovations and fundamental research into
climate dynamics and theory. Such research would not only support improved climate modeling systems, but would also lay the foundations for disruptive advancesin our understanding of the climate system and our ability to predict emergent phenomena such as abrupt climate change. With climate science focusing on climate
model outputs rather than on climate dynamics and theory, we’ve lost a generationof climate dynamicists. As a result, we are lacking the intellectual resources to understand important and challenging issues such as: the effects of the sun on climate,
the network of natural internal variability on multiple timescales, the mathematics
of extreme events, and predictability of a complex system characterized by spatiotemporal chaos.
Decision makers needing regionally-specific climate change information are be12

ing provided with either nothing or potentially misleading predictions from climate
models that are not fit for this purpose. Hoping and expecting to rely on informationfrom climate models about projected regional climate change to guide adaptation
responses has diverted attention from using observational, historical and paleoclimate data from the region to develop the basis for future scenarios. Further, increased
scientific focus on subseasonal (weeks) and seasonal (months) weather/climate forecasts28 could produce the basis for tactical adaptation practices with substantial societal benefits.
How and why did we land between a rock and a hard place on the issue of climate
science? There are probably many contributing reasons, but the most fundamental and profound reason is arguably that both the problem and solution were vastly
oversimplified back in the early 1990s by the UNFCCC, who framed both the problem and the solution as irreducibly global in terms of human-caused global warming. This framing was locked in by a self-reinforcing consensus-seeking approach tothe science and a ‘speaking consensus to power’ approach for decision making thatpointed to a single course of policy action – radical emissions reductions.
The climate community has worked for more than two decades to establish ascientific consensus on human-caused climate change, prematurely elevating a hypothesis to a ruling theory. The IPCC’s consensus-seeking process and its links to
the UNFCCC emissions reduction policies have had the unintended consequence ofhyper-politicizing the science and introducing bias into both the science and related
decision-making processes. The result of this simplified framing of a wicked problem
is that we lack the kinds of information to more broadly understand climate variability
and societal vulnerabilities.
The politicization of climate science has contaminated academic climate researchand the institutions that support climate research, so that individual scientists andinstitutions have become activists and advocates for emissions reductions policies.
Scientists with a perspective that is not consistent with the consensus are at best
marginalized (difficult to obtain funding and get papers published by ‘gatekeeping’
journal editors) or at worst ostracized by labels of ‘denier’ or ‘heretic.’
Policymakers bear the responsibility of the mandate that they give to panels ofscientific experts. In the case of climate change, the UNFCCC demanded of the IPCC
too much precision where complexity, chaos, disagreement and the level current understanding resists such precision. Asking scientists to provide simple policy-readyanswers for complex matters results in an impossible situation for scientists and misleading outcomes for policymakers. Unless policymakers want experts to confirm
their preconceived bias, then expert panels should handle controversies and uncertainties by assessing what we know, what we don’t know, and where the major uncertainties lie.
Imagine if, circa 1990, the UN had framed the climate change problem in the fol13

lowing way:
There are a number of causes of climate change, including manmade causes. Climate science should work to understand all causes of climate variability changethat are relevant on decadal to century timescales, and the impact of climate
variability and change on societies and ecosystems.

Such a framing would have arguably led to better understanding of the climate system and a much more rational approach in developing policies related to reducing
our vulnerabilities to extreme weather and climate variations.
A better social problem-solving framework is needed for managing risk underconditions of deep uncertainty, which employs a broader systems analysis and explicitly incorporates uncertainty to identify paths to a flexible, robust and economicaloutcome. Social science research is needed to analyze ways of incorporating scientificunderstanding with all of its uncertainties into decision making related to complex,
wicked problems.
The war on science
I read Chris Mooney’s book The Republican War on Science 29 shortly after it was published in 2005. It really resonated with me at the time, when I was in the midst of the‘hurricanes and global warming war’. Although the book has ‘Republican’ in the title,much of the content was really about a bipartisan war on science. The ‘war on science’is being fought on two fronts: politicians ignoring science; and using bad science tojustify a political agenda. The notion of ‘war of science’ is also about the naivete ofscientists regarding the role of science and evidence in policy making. 30
With the advent of the Trump administration, concerns about ‘war on science’
have become elevated, with a planned March for Science on 22 April 2017. 31 Why
are scientists marching?32 The scientists’ big concern is ‘silencing of facts’. This concern apparently derives from their desire to have their negotiated ‘facts’ – such as
the IPCC consensus on climate change – dictate public policy. These scientists also
fear funding cuts and challenges to the academic scientific community and the elite
institutions that support it.
The ‘war on science’ that I am most concerned about is the war from within science– scientists and the organizations that support science who are playing power politics
with their expertise and passing off their naïve notions of risk and political opinions as
science. When the IPCC consensus is challenged or the authority of climate science indetermining energy policy is questioned, these activist scientists and organizations
call the questioners ‘deniers’ and claim ‘war on science.’ These activist scientists seemless concerned with the integrity of the scientific process than they are about theirprivileged position and influence in the public debate about climate and energy policy. They do not argue or debate the science – rather, they denigrate scientists who
disagree with them. These activist scientists and organizations are perverting the po14

litical process and attempting to inoculate climate science from scrutiny – this is thereal war on science.

Conclusion
In the midst of disagreement among policy makers about the response to climatechange, climate science has been caught in the crossfire. Challenges to climate research have been exacerbated by unreasonable expectations from policymakers, aswell as by the behavior of climate scientists and professional societies who are using
their professional expertise and preferred political outcomes as the basis for attempting to pervert the political process and inoculate climate science from scrutiny anddebate.
My concern is that the integrity and objectivity of climate research is being compromised. As a result, we have oversimplified the climate change problem and its
solutions. This oversimplification has:• biased scientific research through politicization and funding priorities.
• undercut the political process and dialog necessary for real solutions in a highly
complex world.
We need to rethink the social contract between scientists and government, and develop a new model for policy-relevant science. This is needed to ensure the integrityof science and to improve the basis for science to inform the policy process. Here aresome recommendations:
1. Embrace science as an iterative process, not a collection of ‘facts’. Scientists thatengage the public across the political spectrum and invite them to engage inthe process of science can help build public support for science.
2. New incentive structures for scientists working in fields that are policy relevant
can focus on careful management of bias and uncertainty, public engagement,
responsible interactions with the media, and participation in the policy process
as an honest broker.
3. Scientists interested in engaging with the policy process need a much better
understanding of the policy process, the role that science plays, and how complexity, pluralism and uncertainty in science is accommodated in the policy process.
4. Scientists need better guidelines on the ethical implications of using their expertise for political purposes and a code of conduct for communicating uncertainty and responsibilities for making public statements related to their expertise.
5. Bias and advocacy by institutions such as professional societies is a major concern for the integrity of science.
15

6. For policy-relevant science and regulatory science, more formal methods of
uncertainty characterization and management should be used in scientific research and assessments.
7. For policy-relevant and/or regulatory science where there is substantial uncertainty or disagreement about key conclusions, a Red Team or Team B approach
for assessments can clarify the strength of the arguments and key areas of disagreement. Avoid consensus-seeking approaches.
8. Narrow framing of research priorities on topics where there are widespread uncertainties and debate can bias the research. Funding for Red Team or Team B
approaches would help overcome such systematic biases.
9. Funding priorities in climate research that support observing systems (surface
and satellite-based), fundamental climate dynamics research and research to
improve short-term climate predictions (sub-seasonal to interannual) would
support improved climate models and lay the foundations for disruptive advances in our understanding of the climate system and our ability to predict
emergent phenomena such as abrupt climate change.
10. A better social problem-solving framework that employs a broader systems analysis and explicitly incorporates uncertainty can provide paths to flexible, robustand economical outcomes.
I’m hoping that these recommendations and this hearing will open up a dialogue on
how the federal government can better support research into the complex climate
system that in turn supports improved policy outcomes in reducing our vulnerability
to climate variability.

16

Notes
1. https://judithcurry.com/category/scientific-method/.
2. Curry JA and Webster PJ (2011) Climate science and the uncertainty monster. Bull Amer
Meteorol. Soc., 92: 1667–1682.
3. Curry J (2017) Climate Models for the Layman http://www.thegwpf.org/content/uploads/
2017/02/Curry-2017.pdf.
4. Mosher S and Fuller T (2010) Climategate: The CRUTape letters https://www.amazon.com/
dp/B003552M76/.
5. Nuzzo R (2015) ‘How scientists fool themselves – and how they can stop’ Nature 526: 182.
http://www.nature.com/news/how-scientists-fool-themselves-and-how-they-can-stop-1.18517
6. Foreword to Science on the Verge http://www.andreasaltelli.eu/file/repository/Foreword_
Dan_Sarewitz.pdf.
7. Curry JA, (2013) ‘Climate change: No consensus on consensus’. CAB Reviews 8: 001.
8. Kelly T (2005) ‘The epistemic significance of disagreement’. Epistemology 19: 179–209
9. Kelly T (2008) ‘Disagreement, dogmatism and belief polarization’. J Philosophy 105: 611–
633
10. http://www.auburn.edu/~tds0009/Articles/Chamberlain%201965.pdf.
11. http://www.aps.org/policy/statements/upload/climate-seminar-transcript.pdf.
12. http://www.climatedialogue.org/.
13. Curry JA (2011) ‘Reasoning about climate uncertainty’. Climatic Change 108: 723–732
14. Curry JA (2011) ‘Nullifying the climate null hypothesis’. WIRES Climate Change 2: DOI:
10.1002/wcc.141
15. http://www.cnbc.com/2017/03/09/epa-chief-scott-pruitt.html.
16. https://www.theguardian.com/environment/2017/mar/09/epa-scott-pruitt-carbon-dioxideglobal-warming-climatechange.
17. Oreskes N (2007) ‘The scientific consensus: how do we know we’re not wrong?’ Climatic
Change http://www.cpp.edu/~aebresnock/aebres/ec435/oreskespaper.pdf.
18. Johnson, J (2010) ‘Global warming advocacy science: a cross examination’. http://scholarship.
law.upenn.edu/faculty_scholarship/315/.
19. http://sciencepoliticsclimatechange.blogspot.com/2006/10/puzzle-analogy.html.
20. http://sciencepoliticsclimatechange.blogspot.com/2006/10/house-of-cards-analogy.html.
21. NAS (2006) Surface Temperature Reconstructions for the last 2000 Years. National Academy
Reports https://www.nap.edu/read/11676/chapter/1.
22. Curry JA (2011) ‘Reasoning about climate uncertainty’. Climatic Change 108, 723–732
http://link.springer.com/article/10.1007/s10584-011-0180-z.
23. Curry J ‘Reasoning about climate uncertainty’, op. cit
24. Webster P et al. (2005) ‘Changes in tropical cyclone number, duration and intensity’.
Science. http://science.sciencemag.org/content/309/5742/1844.full.
25. Curry JA et al. (2006) ‘Mixing politics and science in testing the hypothesis that greenhouse warming is causing an increase in hurricane intensity’. Bull. Amer. Meteorol. Soc. http://journals.ametsoc.org/doi/abs/10.1175/BAMS-87-8-1025.
26. UNFCC Treaty (1992) https://unfccc.int/resource/docs/convkp/conveng.pdf.

1727. Curry J (2017) Climate Models for the Layman http://www.thegwpf.org/content/uploads/
2017/02/Curry-2017.pdf.
28. https://www.nap.edu/catalog/21873/next-generation-earth-system-prediction-strategiesfor-subseasonal-to-seasonal
29. Mooney C (2005) The Republican War on Science http://www.waronscience.com/home.
php.
30. https://www.amazon.com/Politics-Evidence-Based-Policy-Making/dp/1137517808.
31. http://www.marchforscience.com.
32. https://www.theguardian.com/us-news/2017/feb/19/epa-trump-boston-science-protest.

18

2 Testimony of Professor John Christy
Summary‘Science’ is not a set of facts but a process or method that sets out a way for us to discover information and which attempts to determine the level of confidence we might
have in that information. In the method, a ‘claim’ or ‘hypothesis’ is stated such thatrigorous tests might be employed to test the claim to determine its credibility. If theclaim fails a test, the claim is rejected or modified then tested again. When the ‘scientific method’ is applied to the output from climate models of the Fifth Assessmentof the UN’s Intergovernmental Panel on Climate Change (IPCC AR5), specifically thebulk atmospheric temperature trends since 1979 (a key variable with a strong and obvious theoretical response to increasing GHGs in this period), I demonstrate that theconsensus of the models fails the test to match the real-world observations by a significant margin. As such, the average of the models is considered to be untruthful inrepresenting the recent decades of climate variation and change, and thus would beinappropriate for use in predicting future changes in the climate or for related policy
decisions.
The IPCC inadvertently provided information that supports this conclusion by• showing that the tropical trends of climate models with extra greenhouse gases
failed to match actual trends• showing that climate models without extra greenhouse gases agreed with actual trends.
A report of which I was a co-author demonstrates that a statistical model that uses
only natural influences on the climate also explains the variations and trends since
1979 without the need of extra greenhouse gases. While such a model (or any climate
model) cannot ‘prove’ the causes of variations, the fact that its result is not rejectedby the scientific method indicates it should be considered when trying to understand
why the climate does what it does. Deliberate consideration of the major influencesby natural variability on the climate has been conspicuously absent in the current
explanations of climate change by the well-funded climate science industry.
One way to aid Congress in understanding more of the climate issue than what
is produced by biased ‘official’ panels of the climate establishment is to organize andfund credible ‘red teams’ that look at issues such as natural variability, the failure of climate models and the huge benefits to society from affordable energy, carbon-based
and otherwise. I would expect such a team would offer to Congress some very different conclusions regarding the human impacts on climate.

19

Introduction
I am John R. Christy, Distinguished Professor of Atmospheric Science, Alabama’s State
Climatologist and Director of the Earth System Science Center at The University of Alabama in Huntsville. I have served as lead author, contributing author and reviewer ofUnited Nations IPCC assessments, have been awarded NASA’s Medal for Exceptional
Scientific Achievement, and in 2002 was elected a fellow of the American Meteorological Society.
It is a privilege for me to offer my analysis of the current situation regarding atmospheric temperature datasets and whether the traditional scientific method using
these datasets has been applied in climate science regarding the pronouncements
about climate change used in policy. I addressed other aspects of climate change including extreme events, crop production, impact of regulation (there is none on the
climate) and data confidence in my last Senate 1 and House2 appearances.
My research area might be best described as building datasets from scratch toadvance our understanding of what the climate is doing and why – an activity I began
as a teenager over 50 years ago. I have used traditional surface observations as wellas measurements from balloons and satellites to document the climate story. Manyof our UAH datasets, generated by myself and UAH colleagues Drs Roy Spencer and
W. Daniel Braswell, are used to test hypotheses of climate variability and change.

Applying the scientific method to climate models from the IPCC
AR5
In my last appearance before this committee 3 I addressed the active campaign of negative assertions made against the various sources of data we use to monitor the temperature of the bulk atmosphere. I demonstrated that the main assertions were incorrect and that we can have confidence in the observations and one reason was that
we now have several independent sources from around the world providing data withwhich to inter-compare. In this testimony I shall focus on the temperature of the bulk
atmospheric layer from the surface to about 50,000 ft – a layer which is often called byits microwave profile name ‘TMT’ (temperature of mid-troposphere). This layer is particularly important because it captures the atmospheric region that is anticipated towarm rapidly and unambiguously if greenhouse theory is well-understood. As such,
if the impact of extra greenhouse gases (GHGs) is to be detected, it should be detected here. In Figure 1 I show an example from a climate model simulation 4 of the
anticipated temperature change for the period 1979–2016.
Figure 1 indicates that, according to theory, the tropical region should have experienced significant warming over the past 38 years due to extra GHGs. (There were
102 model runs to check and they all indicated a warming tropical atmosphere, but todifferent degrees, as shown later.) To test this result we follow the traditional scientific20Figure 1: Temperature trends (°C/decade) for 1979–2016 of the cross-section of theatmosphere as simulated by the Canadian Climate Model.
The tropical band (20°S–20°N) is outlined for the bulk layer (surface to 50,000 ft) that
represents the microwave TMT measurement (temperature of mid-troposphere). Thisoutlined-layer is the region of prominent warming for the 1979–2016 period as
depicted in all models and thus is the region to examine relative to observations.
Figure by Rob Junod, UAH.

method in which a claim (hypothesis) is made and then is tested against independent
information to see if the claim can be sustained or whether it is falsified. If the claim
is confirmed, then we generally look for another test to confirm the claim again. Ifmany tests are consistent with the claim, then we may have confidence in it. If theclaim fails a test, we look for reasons why and modify or reject the original claim andstart over. Since the thrust of this hearing is to see how the scientific method wasor was not applied in the pronouncements about climate science, this will serve as
an excellent example because it deals with a foundational climate metric that should
reveal significant change if theory is correct: the temperature of the bulk atmosphere.
21

Observational data used to test climate models
Recall that the results from climate models are simply hypotheses (claims) about how
the climate should have evolved in the past. The claim here is: ‘the bulk atmospherictemperature trend since 1979 of the consensus of the IPCC AR5 climate models represents the actual trend since 1979’. (1979 is the beginning of the satellite temperatureera.) To test this claim we compare the TMT model trends against TMT from several
observational datasets. The first type of observational datatset is built from satellites
that directly measure the bulk atmospheric temperature through the intensity of microwave emissions. These data are essentially global in coverage and monitor the
Earth everyday. There are three sources, UAH (University of Alabama in Huntsville),
RSS (Remote Sensing Systems, San Rafael, CA) and NOAA.
The second type of measurement is produced from the ascent of balloons thatcarry various instruments including thermistors, which monitor the air temperatureas the balloon rises through this layer. From these measurements a value equivalent to the satellite TMT profile is calculated. Balloon stations are not evenly spaced
throughout the Earth, but because the upper air is much more horizontally coherent
in its features than the surface, a few balloons can represent a very large area in termsof temperature variability. The sources of these balloon datasets are RAOBCORE and
RICH (University of Vienna, Austria), NOAA and UNSW (University of New South Wales,
Australia).
Finally, major weather centers around the world generate atmospheric conditions,
every six hours or so of the entire Earth at many vertical levels, called reanalyses. These
products use many sources of data, including satellites and balloons, and merge theobservations with a continuously running general circulation model. From the information at the vertical levels the TMT quantity is generated for an apples-to-apples
comparison with models, satellites and balloons. The sources of the reanalyses are
ERA-I (European Centre for Medium-Range Weather Forecasts (ECMWF) – ReAnlaysisInterim), NASA-MERRAv2 and JRA-55 (Japan ReAnalyses). These three types of systems – satellites, balloons and reanalyses – represent very different means of computing the bulk atmospheric temperature and are provided by independent, international entities, giving us confidence in the observational results.

Testing the claim: applying the scientific method
In Figure 2 we show the evolution of the tropical TMT temperature since 1979 for
102 climate model runs grouped in 32 curves by institution. Some institutions contributed a single simulation, others as many as 18. Multiple runs from a single institution’s model category were averaged into a single time series here. The curves show
the temperature evolution of the atmosphere in the tropical box shown in Figure 1.
22

Figure 2: Five-year averaged values of annual mean (1979–2016) tropical bulk TMT
as depicted by the average of 102 IPCC CMIP5 climate models (red) in 32 institutionalgroups (dotted lines).
The 1979–2016 linear trend of all time series intersects at zero in 1979. Observations
are displayed with symbols: green circles, average of 4 balloon datasets; blue squares, 3satellite datasets; purple diamonds, 3 reanalyses. See text for observational datasets
utilized. The last observational point at 2015 is the average of 2013–2016 only, while allother points are centered 5-year averages.

Here we have climate model results (i.e. ‘claims’ or ‘hypotheses’) to compare withobservational datasets in a test to check whether the model average agrees with theobserved data. We test the model average because it represents the consensus of thetheoretical models and is used to develop policy, and is embodied in policy-related
products such as the social cost of carbon, the National Climate Assessment and the
EPA Endangerment Finding.
I provided model and observational information as annual temperature anomalies (both tropical and global) to Dr Ross McKitrick (University of Guelph) who has
published extensively as an applied econometrician on the application of statisticaltechniques to the testing of climate hypotheses. He applied the Vogelsang–Franses
F-test method to these data.5 This method is particularly suitable for determining
23

whether the trends of two time series are equivalent or significantly different. The result found in their 2010 paper indicated model trends were significantly warmer thanobservations for the earlier datasets available at that time.
What we are really testing here are the rates of warming depicted by the models
and the observations for the period 1979–2016. I have simplified a depiction of thetest in Figure 3, so that the rate of warming is directly viewed, showing what the test
is measuring. The basic test question is, ‘Is the red line significantly different from

Figure 3: The linear trends of the average of the climate model simulations (red) andthe averages of the three types of observational datasets described in the text.
the others?’ The results are shown in Table 1; there is no equivalence between themodel average trend and the observational datasets whenever the value of the test
is greater than 84 at the <1% level. As shown, all test values exceed 84, and thus themean model trend is highly significantly different from the observations. The scientific conclusion here, if one follows the scientific method, is that the average model
trend fails to represent the actual trend of the past 38 years by a highly significant
amount. As a result, applying the traditional scientific method, one would accept thisfailure and not promote the model trends as something truthful about the recent
past or the future. Rather, the scientist would return to the project and seek to understand why the failure occurred. The most obvious answer is that the models are24

Table 1: Test for equivalence between the 1979–2016 trend of the mean of 102 CMIP5 climate model simulations and the trends of various observational datasets.
Tropics
Trend Test value

GlobalTrend Test value

Balloons
Satellites
Reanalyses
Average all+0.102+0.136+0.104+0.113+0.111+0.117+0.123+0.117

CMIP5 models+0.274

259
104
157
187

165
149
87
158

+0.216Non-equivalence at the 99% confidence level is indicated by test values greater than 84, shown in red.

simply too sensitive to the extra GHGs that are being added to both the model andthe real world.
We do not use surface temperature as a testable metric because models, to varying degrees, are tuned to agree with the surface temperature observations already– that is, they’ve been given the answer ahead of time – thus a comparison of thesurface would not be a valid scientific test. 6

The IPCC AR5 (2013) displayed a similar result: the models failed
Oddly enough, such an important result (i.e. that models fail the test of representing
the real-world bulk temperature trend) was available to see in the most recent IPCC
AR5. Unfortunately, it was buried in the Supplementary Material of Chapter 10 without comment. In Figure 4, I present the figure that appeared in this IPCC section. I
was a reviewer (a relatively minor position in that report) in the AR5 and had insisted
that such a figure be shown in the main text because of its profound importance, but
the government-appointed lead authors decided against it. They opted to place it in
the Supplementary Material, where little attention would be paid, and to fashion thechart in such a way as to make it difficult to understand and interpret. I have taken thesame information in Figure 4 (the IPCC’s AR5 Fig. 10.SM.1) and simplified the presentation so as to be clearer; see Figure 5. The trends here represent trends at different
levels of the tropical atmosphere from the surface up to 50,000 ft. The gray lines are
the bounds for the range of observations, the blue for the range of IPCC model results
without extra GHGs and the red for IPCC model results with extra GHGs.
What is immediately evident is that the model trends in which extra GHGs areincluded lie completely outside of the range of the observational trends, indicating
again that the models, as hypotheses, failed a simple ‘scientific-method’ test applied
to this fundamental climate-change variable. That this information was not clearly
and openly presented in the IPCC is evidence of a political process that was not rep25

Figure 4: Figure 10.SM.1 of the IPCC AR5 Supplementary Material for Chapter 10.
These are trends (1979–2010) for various vertical levels of the atmosphere from:(a) observations (gray band – difficult to see); (b) models without extra GHGs (blueband); (c) models with extra GHGs and other forcings (red band). The lower portion of
the tropical chart (second panel from left) is simplified in Figure 5 and used for thefollowing discussion.

resentative of the dispassionate examination of evidence as required by the scientificmethod. Further, (and this took guts) the IPCC then claimed high confidence in knowing why the climate evolved as it did over the past few decades (humans as the maincause) ignoring the fact the models on which that claim was based had failed an obvious and rather easy-to-perform validation test. Incredibly, what Figure 5 shows isthat the bulk tropical atmospheric temperature change is modeled best when no extra GHGs are included – a direct contradiction to the IPCC conclusion that observedchanges could only be modeled if extra GHGs were included.
26

Figure 5: Simplification of IPCC AR5 figure shown in Figure 4 above.
The colored lines represent the range of results for the models and observations. The
key point displayed is the lack of overlap between the GHG model results (red) and theobservations (gray). The non-GHG model runs (blue) overlap the observations almost
completely.

A simple statistical model that passed the same ‘scientificmethod’ test
The IPCC climate models performed best versus observations when they did not include extra GHGs, and this result can be demonstrated with a statistical model aswell. I was co-author of a report which produced such an analysis. 7 In this report
we examine annual estimates from many sources of global and tropical deep-layer
temperatures since 1959 and since 1979, utilizing explanatory variables that did notinclude rising carbon dioxide concentrations. We applied the model to estimates ofglobal and tropical temperature from the satellite and balloon sources, individually,as shown in Figure 2. The explanatory variables are those that have been known for27

decades, such as indices of El Niño-Southern Oscillation (ENSO), volcanic activity, andsolar activity.8 One of the ENSO explanatory variables was the accumulated MEI (Multivariate ENSO Index,9 in which the index was summed through time to provide anindication of its accumulated impact. This ‘accumulated-MEI’ was shown to be a potential factor in global temperatures by Spencer and Braswell, 10 Interestingly, later
work has shown that this ‘accumulated-MEI’ has virtually the same impact as the accumulated solar index, both of which generally paralleled the rise in temperatures
through the 1980s and 1990s and the slowdown in the 21st century. Thus our report
would have the same conclusion with or without the ‘accumulated-MEI.’
The basic result of this report is that the temperature trend of several datasets
since 1979 can be explained by variations in the components that naturally affectthe climate, just as the IPCC inadvertently indicated in Figure 5. The advantage ofthe simple statistical treatment is that the complicated processes, such as clouds,
ocean-atmosphere interaction, aerosols, etc., are implicitly incorporated by the statistical relationships discovered from the actual data. Climate models attempt to calculate these highly non-linear processes from imperfect parameterizations (estimates),
whereas the statistical model directly accounts for them since the bulk atmospherictemperature is the response-variable these processes impact. It is true that the statistical model does not know what each sub-process is or how each might interact withother processes. But it also must be made clear: it is an understatement to say that no
IPCC climate model accurately incorporates all of the non-linear processes that affectthe system. I simply point out that because the model is constrained by the ultimate
response variable (bulk temperature), these highly complex processes are included.
The fact that this statistical model explains 75–90% of the real annual temperature
variability, depending on dataset, using these influences (ENSO, volcanoes, solar) is anindication the statistical model is useful. In addition, the trends produced from thisstatistical model are not statistically different from the actual data (i.e. passing the‘scientific-method’ trend test, which assumes the natural factors are not influenced
by increasing GHGs). This result promotes the conclusion that this approach achieves
greater scientific (and policy) utility than elaborate climate models, which on averagefail to reproduce the real world’s global average bulk temperature trend since 1979.
The over-warming of the atmosphere by the IPCC models relates to a problem
the IPCC AR5 encountered elsewhere. In trying to determine the climate sensitivity,
which is how sensitive the global temperature is relative to increases in GHGs, the
IPCC authors chose not to give a best estimate. (A high climate sensitivity is a foundational component of the last administration’s social cost of carbon.) The reason?
Climate models were showing about twice the sensitivity to GHGs of calculations
based on real, empirical data. I would encourage this committee, and our government in general, to consider empirical data, not climate model output, when dealing
with environmental regulations.
28

Red teams needed because consensus science is not science
One way for Congress to receive better (less biased) information about claims of climate
science is to organize ‘red teams’, as is done in other parts of government and industry
when critical systems, programs or infrastructure are under consideration. I have discussed this idea is several previous congressional hearings. I include here the section describing red teams from my testimony on 20 September 2012 before the Subcommittee
on Energy and Power of the House Committee on Energy and Commerce.
The term ‘consensus science’ will often be appealed to regarding arguments aboutclimate change to bolster an assertion. This is a form of ‘argument from authority.’
Consensus, however, is a political notion, not a scientific notion. As I testified to the Interacademy Council in June 2010, wrote in Nature that same year,11 and documented
in my written House Testimony last year, 12 the IPCC and other similar assessments do
not represent for me a consensus of much more than the consensus of those selected
to agree with a particular consensus. The content of these climate reports is actually
under the control of a relatively small number of individuals – I often refer to themas the ‘climate establishment’ – who through the years, in my opinion, came to act as
gatekeepers of scientific opinion and information, rather than brokers. The voices of
those of us who object to various statements and emphases in these assessments are,by and large, dismissed rather than accommodated. This establishment includes thesame individuals who become the ‘experts’ called on to promote IPCC claims in government reports, such as the Endangerment Finding by the Environmental Protection
Agency. As outlined in my House testimony, 13 these ‘experts’ become the authors andevaluators of their own research relative to research which challenges their work. But
with the luxury of having the ‘last word’ as ‘expert’ authors of the reports, alternative
views vanish.
I’ve often stated that climate science is a ‘murky’ science. We do not have laboratory methods of testing our hypotheses as many other sciences do. As a result,what passes for science includes opinion, arguments-from-authority, dramatic press
releases, and fuzzy notions of consensus generated by preselected groups. This is notscience.
I noticed the House passed an amendment last year to de-fund the IPCC. We know
from the Climategate emails and many other sources that the IPCC has had problems
with those who take different positions on climate change than what the IPCC promotes. There is another way to deal with this, however. Since the IPCC activity isfunded by US taxpayers, I propose that 5–10% of the funds be allocated to a group ofwell-credentialed scientists to produce an assessment that expresses legitimate, alternative hypotheses that have been (in their view) marginalized, misrepresented orignored in previous IPCC reports (and thus EPA and National Climate Assessments).
Such activities are often called ‘red team’ reports and are widely used in government
29

and industry. Decisions regarding funding for red teams should not be placed in thehands of the current ‘establishment’ but in panels populated by credentialed scientists who have experience in examining these issues. Some efforts along this line
have arisen from the private sector. 14 I believe policymakers, with the public’s purse,
should actively support the assembling all of the information that is vital to addressing this murky and wicked science, since the public will ultimately pay the cost of any
legislation alleged to deal with climate.
Topics to be addressed in this red team assessment, for example, would include:• evidence for a low climate sensitivity to increasing greenhouse gases• the role and importance of natural, unforced variability• a rigorous and independent evaluation of climate model output• a thorough discussion of uncertainty• a focus on metrics that most directly relate to the rate of accumulation of heatin the climate system• analysis of the many consequences, including benefits, that result from CO 2 increases• the importance that affordable and accessible energy has to human health andwelfare.
What this proposal seeks is to provide to Congress and other policymakers a parallel, scientifically-based assessment regarding the state of climate science, which addresses issues that heretofore have been un- or under-represented by previous taxpayer funded, government-directed climate reports. In other words, our policymakers need to see the entire range of findings regarding climate change.

In summary‘Science’ is not a set of facts but a process or method that sets out a way for us to discover information and which attempts to determine the level of confidence we might
have in that information. In the method, a ‘claim’ or ‘hypothesis’ is stated such thatrigorous tests might be employed to test the claim to determine its credibility. If theclaim fails a test, the claim is rejected or modified then tested again. When the ‘scientific method’ is applied to the output from climate models of the IPCC AR5, specificallythe bulk atmospheric temperature trends since 1979 (a key variable with a strong andobvious theoretical response to increasing GHGs in this period), I demonstrate thatthe consensus of the models fails the test to match the real-world observations by asignificant margin. As such, the average of the models is considered to be untruthfulin representing the recent decades of climate variation and change, and thus would
be inappropriate for use in predicting future changes in the climate, or for related
policy decisions.
30

The IPCC inadvertently provided information that supports this conclusion by:• showing that the tropical trends of climate models with extra greenhouse gases
failed to match actual trends• showing that climate models without extra greenhouse gases agreed with actual trends.
A report of which I was a co-author demonstrates that a statistical model that uses
only natural influences on the climate also explains the variations and trends since
1979 without the need of extra greenhouse gases. While such a model (or any climate
model) cannot ‘prove’ the causes of variations, the fact that its result is not rejectedby the scientific method indicates it should be considered when trying to understand
why the climate does what it does. Deliberate consideration of the major influencesby natural variability on the climate has been conspicuously absent in the current
explanations of climate change by the well-funded climate science industry.
One way to aid congress in understanding more of the climate issue than what
is produced by biased ‘official’ panels of the climate establishment is to organize andfund credible ‘red teams’ that look at issues such as natural variability, the failure of climate models and the huge benefits to society from affordable energy, carbon-based
and otherwise. I would expect such a team would offer to Congress some very different conclusions regarding the human impacts on climate.

31Notes
1. Commerce, Science and Transportation, 8 December 2015.
2. Science, Space and Technology, 2 February 2016.
3. 2 February 2016
4. Canadian Climate Model run CanESM2_rcp45_r3i1p1.
5. As described in McKitrick RR, McIntyre S and Herman C (2010) ‘Panel and multivariate
methods for tests of trend equivalence in climate data sets’, Atmosph. Sci. Lett. 11. DOI:
10.1002/asl.290.
6. Hourdin FT et al. (2016) ‘The art and science of climate model tuning’, doi:10.1175/BAMS-D00135.1. and Voosen P (2016) ‘Climate scientists open up their black boxes to scrutiny’, 2016,
Science 354: 401–402. DOI:10,1126/Science.354.6311.401).
7. Wallace J et al. (2016) ‘On the existence of a ‘tropical hot spot’ and the validity of
the EPA’s CO2 endangerment finding – Abridged research report’, August 2016 (Available
at https://thsresearch.files.wordpress.com/2016/09/ef-cpp-sc-2016-data-ths-paper-ex-sum090516v2.pdf.)
8. See e.g. Christy J and McNider R (1994) ‘Satellite greenhouse signal’, Nature 367: 325.
9. See https://www.esrl.noaa.gov/psd/enso/mei/.
10. Spencer R and Braswell W (2014) ‘The role of ENSO in global ocean temperature changes
during 1955–2011 simulated with a 1D climate model’, APJ. Atmos. Sci. 50(2): 229–237,
DOI:10.1007/s13143-014-001-z.
11. Christy 2010
12. House Space, Science and Technology, 31 March 201113. 31 March 2011.
14. e.g. the Non-governmental International Panel on Climate Change http://nipccreport.
org/ and Michaels (2012) ADDENDUM:Global Climate Change Impacts in the United States32

3 Testimony of Professor Michael Mann
Mr Chairman, and members of the Committee. My name is Michael Mann. I am Distinguished Professor of Atmospheric Science at Penn State University, and Director of
the Penn State Earth System Science Center. My research involves the use of climate
models, the analysis of empirical climate data, and developing methods for comparing observations and model predictions. The primary focus of my research is understanding the long-term behavior of the climate system, and determining the roles ofvarious potential agents of climate change, both natural and human.
I have served as organizing committee chair for the National Academy of Sciences
Frontiers of Science, and as the co-author or advisor for several National Academy of
Sciences reports related to climate change. I have served as editor for the Journalof Climate of the American Meteorological Society and have served as a member ofnumerous other international and US scientific working groups, panels and steeringcommittees. I was awarded the Hans Oeschger Medal of the European GeophysicalUnion in 2012 and received the Friend of the Planet Award from the National Center for Science Education in 2014. I am a Fellow of the American Geophysical Union,
the American Meteorological Society, and the American Association for the Advancement of Science. I have authored more than 200 publications, and several books including Dire Predictions: Understanding Climate Change, The Hockey Stick and the Climate Wars and The Madhouse Effect: How Climate Change Denial Is Threatening Our
Planet, Destroying Our Politics, and Driving Us Crazy with Tom Toles, the Pulitzer Prizewinning editorial cartoonist for the Washington Post.
Let me first comment about why I went into science. I was fascinated by the natural world as a child and wanted to devote my life to understanding it. This led me ona lifelong journey of scientific discovery that is every bit as thrilling to me today as it
was as a child. When the science has broader societal importance, that’s icing on the
cake.
Earlier this week, for example, my colleagues and I published a study in the journal
Scientific Reports using a combination of observations and climate model simulations
to demonstrate a linkage between climate change and jet stream behavior linked to
extreme, persistent weather events like the 2011 Texas and Oklahoma drought andthe 2015 California wildfires. Continuing to pose questions and to seek to answer
them using scientific tools and observations – that’s what I truly love doing.
But I’m here today because I’m also passionate about communicating what weknow to the public and to policymakers. I have become convinced that no pursuit
could be more noble. So about this hearing: It is important to make clear at the outsetthat there is extremely broad agreement among the world’s scientists on the basic
facts of human-caused climate change. The US National Academy of Sciences, theRoyal Society of the UK, and all of the scientific societies 1 of all of the industrial nations– the more than 30 scientific societies 2 in the US that have weighed in on the matter,33

and at least 97%3 of scientists publishing in the field have all concluded, based on theevidence, that climate change is real, is human-caused, and is already having adverse
impacts on us, our economy, and our planet.
Yet we find ourselves at this hearing today, with three individuals who represent
that tiny minority that reject this consensus or downplay its significance, and only one– myself – who is in the mainstream. That’s 25%, a far cry from the 97–99% figure that
actually characterizes where the world’s scientists stand on this issue. This creates theillusion of a debate that does not exist. This is not an auspicious start for a hearing that
purports to be examining science rather than antiscience, fact rather than fiction.
I coined the term ‘Serengeti Strategy’ back in 2012 in The Hockey Stick and the
Climate Wars 4 to describe how industry special interests who feel threatened by scientific findings – be it tobacco and lung cancer, or fossil fuel burning and climatechange – single out individual scientists to attack in much the same way lions of the
Serengeti single out an individual zebra from the herd. In numbers there is strength,
but individuals are far more vulnerable. Science critics will therefore often select asingle scientist to ridicule, hector, and intimidate. The presumed purpose is to set an
example for other scientists who might consider sticking their neck out by participating in the public discourse over certain matters of policy-relevant science.
I should know. I’ve found myself5 at the center of such episodes more than once,
as a result of the iconic ‘Hockey Stick’ that my co-authors and I published in the late
1990s that demonstrates the unprecedented nature of recent warming. While thehockey stick is hardly the basis6 of the case for human-caused climate change, thevisually compelling character of the graphic has made it – and indeed, me – a targetof climate change deniers for years.
In October 2003 just days before a critical US Senate resolution to acknowledge
the threat of human-caused climate change, an ‘article’ was published by climatechange-denial friendly ‘journal’ that engaged in dubious attacks on the hockey stick.
A fossil fuel industry front group published an op-ed trumpeting the specious criticisms in USA Today on the morning of the Senate vote. Senator James Inhofe of ‘climate change is the greatest hoax7 ever perpetrated on the American people’ infamy
happily trumpeted the article during the Senate floor debate. While the critique on
the hockey stick would soon be summarily dismissed, 8 it served the short-term purpose of hijacking the discussion. The bill did not pass.
In 2005, as the House of Representatives was considering energy and climate legislation, Joe Barton (R-TX), Chair of the House Energy and Commerce Committee anda leading recipient of fossil fuel money engaged in what was widely condemned asa ‘witch-hunt’9 against me and my Hockey Stick co-authors. Barton demanded all of
my personal emails and correspondence with other scientists, and numerous othermaterials, in an apparent effort to find something, anything, he could use to try to discredit the iconic Hockey Stick. In the cynical minds of our critics, discrediting our work34

would somehow undermine the entire case for concern over human-caused climatechange.
On the eve of the Copenhagen UN climate summit of December 2009 – seenas the greatest opportunity yet for an international agreement to limit greenhousegas emissions – a trove of emails, including many of my own, had been stolen, andcombed through for words and phrases (like ‘trick’ – a completely appropriate term inscience for a clever approach) that might seem embarrassing or even damning. The
out-of-context snippets were posted on climate change deniers’ websites and thenspread through right-wing blogs and news sites. Soon even mainstream news organizations were credulously parroting the denialist narrative that a few stolen emails
somehow called into question the fundamental evidence behind human-caused climate change, a result of nearly two centuries 10 of scientific research. I and a small
number of other leading climate scientists found ourselves at the very center of thesmear campaign.
At least 10 investigations and reviews have established 11 that there was no wrongdoing on the part of the scientists (indeed, the only wrongdoing was the criminal
theft of the emails in the first place). The vindications, however, occurred long after
fossil fuel interests and those doing their bidding had the opportunity to sabotage
efforts to reach an international agreement limiting carbon emissions (Oil-rich Saudi
Arabia, for example, insisted12 in Copenhagen that the stolen emails justified opposition to any agreement to limit carbon emissions; Russia also appears to have playedsome role in the hacking and/or dissemination of the emails).
We now have the latest in this perpetual series of bad-faith assaults on climate
science, and the story is eerily familiar. The attacks, as always, have focused on a particular individual – in this case, Tom Karl, 13 the recently retired Director of NOAA’s
National Climatic Data Center and a scientist for whom I have the deepest respect.
For proper context, we must consider the climate denial myth du jour that global
warming has ‘stopped’. Like most climate denial talking points, the reality is prettymuch the opposite of what is being claimed by the contrarians. All surface temperature products, including the controversial UAB satellite temperature record, show
a clear long-term warming trend over the past several decades (Figure 1). We havenow broken the all-time global temperature record for three consecutive years 14 anda number of published articles have convincingly demonstrated that global warming has continued unabated despite when one properly accounts for the vagaries ofnatural short-term climate fluctuations. A prominent such study 15 was published by
Tom Karl and colleagues in 2015 in the leading journal Science. The article was widely
viewed as the final nail in the ‘globe has stopped warming’ talking point’s coffin. Lastmonth, opinion writer David Rose of the British tabloid the Daily Mail – known for16
his serial misrepresentations of climate change and his serial attacks on climate scientists – published a commentary17 online attacking Tom Karl, accusing him of having
35

Figure 1: Comparison of the various surface or lower atmospheric temperaturerecords during past few decades (graph by Peter Jacobs of George Mason University).

‘manipulated global warming data’ in the 2015 Karl et al article. This fake news story
was built entirely on an interview with a single disgruntled former NOAA employee,
John Bates, who had been demoted from a supervisory position at NOAA for his inability to work well with others.
Bates’ allegations were also published on the blog of climate science denier Judith Curry (I use the term carefully – reserving it for those who deny the most basic
findings of the scientific community, which includes the fact that human activity is
substantially or entirely responsible for the large-scale warming we have seen overthe past century – something Judith Curry 18 disputes19 ). That blog post and the Daily
Mail story have now been thoroughly debunked by the actual scientific community. 20
The Daily Mail claim that data in the Karl et al. Science article had been manipulated
was not supported by Bates. When the scientific community pushed back on the untenable ‘data manipulation’ claim, noting that other groups of scientists had independently confirmed21 Karl et al’s findings, Bates clarified that the real problem was thatdata had not been properly archived and that the paper was rushed to publication.
These claims too quickly fell apart.
Though Bates claimed that the data from the Karl et al study was ‘not in machinereadable form’, independent scientist Zeke Hausfather, lead author of a study 22 that36

accessed the data and confirmed its validity, wrote in a commentary 23 ‘. . . for the life ofme I can’t figure out what that means. My computer can read it fine, and it’s the sameformat that other groups use to present their data’. As for the claim that the paper was
rushed to publication, Editor-in-chief of Science Jeremy Berg says, ‘With regard to the“rush” to publish, as of 2013, the median time from submission to online publication
by Science was 109 days, or less than four months. The article by Karl et al. underwent
handling and review for almost six months. Any suggestion that the review of thispaper was ‘rushed’ is baseless and without merit. Science stands behind its handlingof this paper, which underwent particularly rigorous peer review.’
Shortly after the Daily Mail article went live, a video attacking Karl (and NOAA andeven NASA for good measure) was posted by the Wall Street Journal. Within hours, theDaily Mail story spread like a virus through the right-wing blogosphere, appearing
on numerous right-wing websites and conservative news sites. It didn’t take long forthe entire Murdoch media empire in the US, UK and elsewhere to join in, with theexecrable Fox News for example alleging24 Tom Karl had ‘cooked’ climate data and,with no sense of irony, for political reasons.
Rep. Lamar Smith (R-TX), chair of this committee has a history 25 of launching attacks on climate science and climate scientists. He quickly posted a press releasepraising the Daily Mail article, placing it on the science committee website, and falsely
alleging that government scientists had ‘falsified data’. Smith, it turns out, had beenplanning a congressional hearing timed to happen just days after this latest dustup,
intended to call into question26 the basis for the EPA regulating carbon emissions.
His accusations against Karl and NOAA of tampering with climate data was used inthat hearing to claim that the entire case for concern over climate change was now
undermined.
Of course, even if the Karl study was completely wrong, it wouldn’t in any way
alter what we know about climate change. Just as our critics have intentionally ignored the many independent studies reaffirming 27 the ‘Hockey Stick’ curve in thepeer-reviewed scientific literature (see Figure 2), so too have Karl’s critics ignored that
his findings have been replicated and confirmed by other research groups publishing in the peer-reviewed literature. That includes the study 28 led by Zeke Hausfatherof the ‘Berkeley Earth’ project – a project funded in part by the Koch Brothers andincluding29 as one of its original team members, climate change contrarian Judith
Curry. The authors showed that the Karl et al. estimates agree with the best available
independent estimates of ocean warming (see Figure 3). Lead author Hausfather has
stated30 that ‘The fact that the new NOAA record is effectively identical with records
constructed only from higher quality instruments (buoys, satellite radiometers, andArgo floats) strongly suggests that NOAA got it right and that we have been underestimating ocean warming in recent years.’ Let me make some additional observations with regard to this latest episode. Climate contrarians like to accuse scientists
37

Figure 2: PAGES 2k temperature reconstruction published by team of 78 scientists
around the world using the most widespread paleoclimate database to date (Ahmed
et al., Nature Geoscience, 2014) shown (green) along with the original Mann et al
1999 ‘Hockey Stick’ reconstruction (blue), and instrumental (HadCRUT4) temperaturerecord (red). Blue shading indicates uncertainty in the Mann et al temperature reconstruction (graph by Klaus Bitterman of Potsdam Institute for Climate Studies).

of understating uncertainty. Anyone who knows scientists and is familiar with scientific research understands how absurd that accusation is. Scientists embrace theconcept of uncertainty, because it guides us – it informs our choices of what additional measurements to make and hypotheses to pursue. I would note that our 1999
‘Hockey Stick’ article that is so much maligned by climate change deniers, contained
the words ‘uncertainties’ and ‘limitations’ in the title. Let me also remind you that the
implications of scientific ‘uncertainty’ are rather different from what your contrarian
witnesses would like you to believe. Leading economists like Harvard’s Marty Weitzman have shown that31 uncertainty is most likely a reason for even more concerted
action to mitigate climate change because of what is known as the ‘heavy tail’ of the38

Figure 3: Global sea surface temperatures from the old NOAA record (ERSSTv3b), the
new NOAA record (ERSSTv4), and instrumentally homogenous records from buoys
and satellites. See Hausfather et al. (2017) for details, as well as comparisons withshorter Argo-based records.
distribution of risk, namely the huge potential costs if the impacts turn out to be evengreater than predicted, something that appears to be the case now with the potential
rapid collapse32 of the West Antarctic Ice Sheet and the increased sea level rise thatwill come with it.
Contrarians also falsely accuse scientists of conspiring to enforce ‘dogma’. But theway scientists get articles in leading journals like Science or Nature is by demonstrat39

ing something novel – something we didn’t already know, not by simply reiterating
what is known. And herein lies a conundrum for those attacking the Karl et al. study.
One of the articles seized upon in a previous hearing by Chairman Smith as a supposed indictment of Karl et al. is a Nature Climate Change article33 (Fyfe et al 2016) on
which I was a co-author. As a co-author of this article, I can assure you that it in noway calls into question the integrity of NOAA’s data, or the honesty of Tom Karl andhis colleagues, whom I hold in the highest esteem. We simply differed with them on
the best interpretation of the temperature record, demonstrating that the interpretation of whether or not there was a temporary slowdown in warming during the first
decade of the 21st century depends on precisely how the baseline warming trend isdefined.
Chairman Smith can’t have it both ways. This study can’t both be an indictmentof Tom Karl and colleagues and at the same time support the Chairman’s conspiracy theories about climate scientists colluding with each other and being compromised by ‘groupthink’. What our Nature Climate Change piece actually demonstrates
is that there is indeed a robust, healthy, and respectful debate among scientists whenit comes to interpreting data and testing hypotheses. True scientists are skeptics– real skeptics, contesting prevailing paradigms and challenging each other, in thepeer-reviewed literature, at scientific meetings, and in seminars – the proper channels for good faith scientific debate. That, of course, is inconvenient to the caricaturethat Congressman Smith and his contrarians witnesses have sought to paint when it
comes to climate science and climate scientists.
While we’re at it, let me address another favorite talking point of the critics, theclaim that climate models we use to project future climate change are unreliable anduntested. The reality is that the models have been tested vigorously and rigorously
in numerous ways, and have passed a number of impressive tests in the past, such
as James Hansen’s famous successful predictions 34 from the 1980s and 1990s. Let metake the opportunity to bring your attention to one particular analysis 35 that appears
in the latest issue of Nature Climate Change. Back in 1989, legendary climate scientists
Ron Stouffer (a graduate of our program at Penn State I’m proud to say) and Suki
Manabe made a prediction not just of the average warming of the globe, but of the
precise global pattern of that warming. That pattern matches the observed patternof warming that has ensued remarkably well (see Figure 4).
When I was attacked by Joe Barton36 a little more than decade ago over the hockey
stick, at a time when both houses of Congress and the presidency were in the hands ofRepublicans, I found support in the hands of both the Bush Administration’s Office of
Science and Technology Policy, and moderate, pro-science, pro-environment Republicans in the Senate and House such as John McCain (R-AZ) and Sherwood Boehlert(R-NY). Mr. Boehlert was the Republican Chairman of this Committee, the Science
Committee, at the time. Where are these good faith conservatives today? Why are40they not speaking out against this latest abuse against science and reason? If they
fail to force their concerns, we must worry just how far down the antiscience rabbit
hole we’ll be going this time.
There is a worthy debate to be had about climate policy. And I am deeply appreciative of the efforts of conservatives like Bob Inglis 37 of South Carolina, former Reagan administration officials James Baker and George Schultz, 38 and Republican-led
groups like RepublicEN39 and the Niskanen Center40 to promote conservative solutions to solving the climate problem. It is time for other Republicans to put aside theantiscience and engage instead in the worthy debate to be had about how we solve
this great challenge to all of humanity.

41

Figure 4: Pattern of warming predicted by climate model simulations performed
in1989 (top) compared with observed pattern (bottom) of warming (from Stoufferand Manabe, Nature Climate Change, 2017).

42

Biography of Michael E. Mann
Dr Michael E. Mann is Distinguished Professor of Atmospheric Science at Penn State
University, with joint appointments in the Department of Geosciences and the Earthand Environmental Systems Institute (EESI). He is also director of the Penn State Earth
System Science Center (ESSC). Dr Mann received his undergraduate degrees in physics
and Applied Math from the University of California at Berkeley, an M.S. degree inphysics from Yale University, and a PhD in Geology and Geophysics from Yale University. His research involves the use of theoretical models and observational data
to better understand Earth’s climate system. Dr Mann was a Lead Author on the Observed Climate Variability and Change chapter of the Intergovernmental Panel on Climate Change (IPCC) Third Scientific Assessment Report in 2001 and was organizing
committee chair for the National Academy of Sciences Frontiers of Science in 2003. He
has received a number of honors and awards including NOAA’s outstanding publication award in 2002 and selection by Scientific American as one of the fifty leading
visionaries in science and technology in 2002. He contributed, with other IPCC authors, to the award of the 2007 Nobel Peace Prize. He was awarded the Hans Oeschger
Medal of the European Geosciences Union in 2012 and was awarded the National
Conservation Achievement Award for science by the National Wildlife Federation in
2013. He made Bloomberg News’ list of fifty most influential people in 2013. In 2014,
he was named Highly Cited Researcher by the Institute for Scientific Information (ISI)
and received the Friend of the Planet Award from the National Center for Science
Education. He is a Fellow of the American Geophysical Union, the American Meteorological Society, and the American Association for the Advancement of Science. He
is also a co-founder of the award-winning science website RealClimate.org.
Dr Mann is author of more than 200 peer-reviewed and edited publications, andhas published three books including Dire Predictions: Understanding Climate Change,
The Hockey Stick and the Climate Wars and most recently, The Madhouse Effect with
Washington Post editorial cartoonist Tom Toles.

43

Notes
1. Joint science academies’ statement: ‘Global response to climate change’, 2005
2.
‘Scientific consensus on global warming’, Union of Concerned Scientists: http://www.ucsusa.org/global_warming/science_and_impacts/science/scientific-consensuson.html#.WNfu6I61v_Q
3. Cook J et al. (2016) Environ. Res. Lett. 11: 048002.
4. Mann ME (2012) The Hockey Stick and the Climate Wars, Columbia University Press
5. Ibid, 4.
6. Rahmstorf S (2005) ‘What if . . . the ‘Hockey Stick’ were wrong? RealClimate.org, 27 January
2005.
7. Romm J (2011) ‘Inhofe: Calling climate change “the greatest hoax ever” Is ‘doing the Lord’s
work’. Climate Progress, 5 December 2011.
8. Vergano D (2003) ‘Global warming debate heats up Capitol Hill’ USA Today, 18 November
2003.
9. Brown P (2005) ‘Republicans accused of witch-hunt against climate change scientists’
Guardian, 30 August 2005.
10. Mason J (2012)‘Two centuries of climate science: Part One – Fourier to Arrhenius, 1820–
1930’ Skeptical Science, 26 April 2012.
11. ‘Debunking misinformation about stolen climate emails in the “Climategate” manufactured controversy’, Union of Concerned Scientists: http://www.ucsusa.org/global_warming/
solutions/fight-misinformation/debunking?misinformation?stolen?emails?climategate.
html.
12. Henig J (2009) ‘Climategate’: Hacked e-mails show climate scientists in a bad light but
don’t change scientific consensus on global warming. FactCheck.org, 10 December 10.
13. ‘Tom Karl retires after nearly 41 years of service’, NOAA press release, 4 August 2016.
14. Patel JK (2017) ‘How 2016 became Earth’s hottest year on record’ New York Times, 18
January 2017.
15. Karl T et al. (2015) ‘Possible artifacts of data biases in the recent global surface warming
hiatus’, Science, 348: 1469–1472.
16. See the DeSmogBlog entry for David Rose: https://www.desmogblog.com/david?rose
17. Rose D (2017) ‘Exposed: How world leaders were duped into investing billions over manipulated global warming data’ Daily Mail (UK), 4 February 2017.
18. Eilperin J and Dennis B (2017) ‘Scott Pruitt’s office deluged with angry callers after hequestions the science of global warming’ Washington Post, 11 March 2017.
19. Schmidt G (2014) ‘IPCC attribution statements redux: A response to Judith Curry’ RealClimate.org, 27 August 2014.
20.
‘Climate change, science, NOAA falsely maligned by tabloid spin’ Climate Nexus,
http://climatenexus.org/messaging?communication/current?events/climate?change?
science?noaa?falsely-maligned?tabloid?spin
21. Hausfather Z et al. (2017) ‘Assessing recent warming using instrumentally homogeneous
sea surface temperature records’, Science Advances, 3: e1601207.
22. Ibid 21.

44

23. Hasufather Z (2017)‘Factcheck: Mail on Sunday ’s Śastonishing evidence’ about global
temperature rise’, Carbon Brief, 5 February 2017 https://www.carbonbrief.org/factcheck?mail?
sundays?astonishing?evidence-global?temperature?rise.
24. ‘Federal scientist cooked climate change books ahead of Obama presentation, whistle
blower charges’, Fox News, 17 February 2017).
25. Mann ME (2015) ‘The assault on climate science’ New York Times, 8 December 2015.
26. Collier K (2017) ‘Global warming skeptic Lamar Smith sets “Make EPA great again” hearing’Texas Tribune, 2 February 201727.
Rahmstorf S (2013) ‘Most comprehensive paleoclimate reconstruction confirms
Hockey Stick’ Climate Progress, 8 July 2013 https://thinkprogress.org/most?comprehensive?
paleoclimate-reconstruction?confirms?hockey?stick?e7ce8c3a2384#.p1bm8mmfd.
28. Ibid 21.
29. Sourcewatch page on Judith Curry: http://www.sourcewatch.org/index.php/Judith_Curry.
30. Ibid 23.
31. Weitzman M (2011) ‘Fat-tailed uncertainty in the economics of catastrophic climatechange’ Symposium on Fat Tails and the Economics of Climate Change, Oxford University
Press, 2011.
32. Gillis J (2016) ‘Climate model predicts West Antarctic Ice Sheet could melt rapidly’ New
York Times, 30 March 2016.
33. Fyfe J. et al. (2016) ‘Making sense of the early?2000s warming slowdown’ Nature Climate
Change, 6: 224-Ű228.
34. Schmidt G (2007) ‘Hansen’s 1988 projections’ RealClimate.org, 15 May 2007 http://www.
realclimate.org/index.php/archives/2007/05/hansens?1988?projections/35. Stouffer RJ and Manabe S (2017) ‘Assessing temperature pattern projections made in
1989’, Nature Climate Change, 7: 163–166.
36. Ibid 4.
37. JFK ‘Profile In Courage’ Award Announcement (2015): https://www.jfklibrary.org/Events?
and-Awards/Profile?in?Courage?Award/Award?Recipients/Congressman?Bob?Inglis?2015.
aspx
38. Mooney C and Eilperin J (2017) ‘Senior Republican statesmen propose replacing Obama’s
climate policies with a carbon tax’ Washington Post, 8 February 2017.
39. RepublicEN.org: http://www.republicen.org/.
40. Niskanen Center: https://niskanencenter.org/.

45

4

Testimony of Professor Roger Pielke Jr

My testimony focuses on how members of Congress can better support scientific integrity in climate research and the steps that members can take to avoid contributing
to the pathological politicization of science.

Take-home points• Science offers a powerful set of methods, evidence and an orientation to knowledge that can be essential to effective decision making.
• The science and policy communities have together over many decades developed highly credible, legitimate and relevant mechanisms for the assessmentof the state of knowledge in any area of relevance to decision making.
• The legislative process is essential to a well-functioning democracy, but it is notwell suited to the reliable characterization of the overall state of knowledge ona particular topic.
• How elected officials chose to utilize assessment and legislative processes forcharacterizing knowledge has great influence over the degree to which science
becomes pathologically politicized.
• Ultimately, on complex, political issues like climate policy, reaching agreement
on matters of science is neither necessary nor sufficient for policy action to occur.

My recent experiences where science meets politics
Despite publishing many peer reviewed papers on a wide range of climate-related
topics with colleagues around the world and having my research included in the reports of the Intergovernmental Panel for Climate Change (IPCC), 1 I experienced anorganized effort of delegitimization by members of Congress and the White House,
supported by their political allies in the media and in well-funded advocacy groups.
These efforts were successful in that they resulted in me re-orienting my academic
career away from climate-related research.
Here are some specifics of my experiences over the past few years:• Several months after I testified before this committee in December, 2013, theWhite House posted on its website a six-page essay by the President’s Science
Advisor, John Holdren, which claimed falsely that my testimony before this committee was ‘not representative of mainstream views on this topic in the climatescience community’ and was ‘seriously misleading.’ 246• Science advisor Holdren’s false claims were put forward even though my testimony was drawn from and consistent with the most recent reports of the IPCC.
I have for decades supported the scientific assessment process of the IPCC anddid so explicitly in my 2013 Congressional testimony.
• One year later, Congressman Raul Grijalva (D-AZ) opened a formal investigation of me and six other professors (three of us are testifying here today). In his
letter to my university’s president, Mr. Grijalva justified the investigation of me
by relying on the science advisor’s false claims: ‘John Holdren, director of theWhite House Office of Science and Technology Policy, has highlighted what hebelieves were serious misstatements by Prof. Pielke of the scientific consensus
on climate change,’ and cited Dr. Holdren’s essay on the White House website. 3• In his letter, Mr. Grijalva introduced another false implication – that I, and theother academics, had ‘potential conflicts of interest and failure to disclose corporate funding sources.’4 Mr. Grijalva’s letter cited Exxon Mobil and the Koch
Foundation as possible sources of undisclosed funding that I may have received.
• The communications director for the House Natural Resources Committee explained how we seven academics were chosen to be investigated by Mr. Grijalva: ‘The way we chose the list of recipients [of Mr. Grijalva’s letter] is who has
published widely, who has testified in Congress before, who seems to have themost impact on policy in the scientific community.’ 5• Publishing widely, testifying before Congress when asked and doing work with
policy impact are usually held up as virtues among academics who are supported with public funds, but not in this circumstance.
• My university conducted the investigation as requested by Mr. Grijalva, and (nosurprise to me) found that I have never received any fossil fuel or Koch Foundation funding. In 2016, the University of Colorado’s elected Board of Regentsissued a statement of support for me and academic freedom more generally. 6• Despite being ultimately vindicated about the integrity my research and myfunding sources, as well as receiving the strong support of my university’s leadership, the investigation proved extremely harmful to my ability to work in thefield of climate.
• I have academic tenure (thankfully) and have chosen to shift the focus of myresearch to other interesting subjects at the intersection of science, policy andpolitics.
• Further details of my experiences can be found in an op-ed, included as Appendix A to this testimony.
47

Lessons of my experience• Scientific evidence in support of the conclusions I presented to this committee
in 2013 is even stronger today. There is little scientific basis in support of claims
that extreme weather events – specifically, hurricanes, floods, drought, tornadoes – and their economic damage have increased in recent decades due tothe emission of greenhouse gases. In fact, since 2013 the world and the UnitedStates have had a remarkable stretch of good fortune with respect to extreme
weather, as compared to the past.
• The lack of evidence to support claims of increasing frequency or intensity ofhurricanes, floods, drought or tornadoes on climate timescales is also supportedby the most recent assessments of the IPCC and the broader peer reviewed literature on which the IPCC is based.
• I have included an update of relevant data and summary conclusions of the
IPCC related to trends in extreme weather as Appendix B to this testimony. †• My experience as an inconvenient academic is not unique. Politicians, including
elected officials in Congress, and enthusiastic advocates from both sides of theaisle have targeted climate researchers whose peer-reviewed research they do
not like – including all four witnesses testifying here today. Such dynamics ofdelegitimization are not unique to the climate issue.
• Academics – no matter how solid their research may be – are no match for wellfunded advocacy groups, activists in the media, the White House or Congress.
• Members of Congress have great power to delegitimize inconvenient experts,
even derail their careers, and in the process, contribute to the pathological politicization of science.
• Members of Congress also have the power to defuse the pathological politicization of science, to uphold scientific integrity and put both science and politics
in their proper places.
• This is a bipartisan challenge, which can only be addressed with a bipartisancommitment to scientific integrity.

Recommendations to improve the state of scientific integrity inclimate science
I have studied and written about science in policy and politics for several decades. I
am a part of an international community of scholars and practitioners who focus on†

48

Appendix B has not been reproduced in this GWPF version of Prof Pielke’s testimony. Interested
readers can find it in the original version as submitted to the House of Representatives. 7

the challenges of science advice to governments. 8 There is consequently a deep bodyof knowledge and evidence on scientific advice – what works, and what does not.
My most well-known contribution to this area of scholarship and practice is The
Honest Broker: Making Sense of Science in Policy and Politics (Cambridge University
Press, 2007). Drawing on my experiences, my research and that of the broader community focused on scientific advice, I offer the following recommendations focusedon how members of Congress can help to improve the state of scientific integrity inclimate science.
• Policymakers and scientists have developed well-established established processes for assessing the state of scientific knowledge on subjects of relevanceto policy makers.
• Such processes include federal advisory committees, the National Academies,
the assessments of the IPCC and many others nationally and internationally.
• There is also an enormous academic literature on the role of scientific assessments in policy and politics. Google Scholar lists almost a million articles under
the key words ‘scientific assessments policy politics’. 9• Assessments of scientific knowledge are most effective when they address questions that policymakers have judged to be relevant to decision making and do
so in a way that is viewed to be authoritative, unbiased and inclusive. 10• Such processes work best when they accurately characterize areas of uncertainty and ignorance, in addition to what is known with greater certainty. Suchaccurate characterization is facilitated when assessment processes are populated by a diversity of experts, including those who may hold minority or unpopular perspectives.
• Members of Congress have the standing and authority to call for such assessments, to ensure through oversight that they are conducted with integrity andare responsive to their information requests.
• In contrast, while the legislative process can be extremely effective in highlighting partisan differences on policy, it is not well suited to provide an accuratecharacterization of the state of scientific understandings.
• Sometimes debates over science serves as a proxy for debates about policy
preferences or political orientation. When members of Congress participate insuch proxy debates, it contributes to the pathological politicization of science.
• Assessments are best conducted outside the spotlight of high stakes politicalconflict.
• There is of course a risk that such assessments might be captured by interests,
fall prey to groupthink or gatekeeping, or fail to accurately represent scientificunderstandings. In such instances the assessment process may become viewed49

as partisan, illegitimate or simply not useful. In my area of expertise this occurred in the Fourth Assessment Report of the IPCC. 11• Climate science is a particularly politicized research area, meaning that carefulattention should be paid to how assessments are organized and who leads andparticipates in them.
• Consequently, oversight of the integrity of these assessments is an importantand appropriate role for Congressional committees, among others.
• However, the investigation of individual researchers (whether governmental on
non-governmental) is not an appropriate role for Congress and is unlikely tocontribute positively to the upholding of scientific integrity.
• A bipartisan truce ending such investigations of individual researchers should
start immediately.
• Congress should support the role of scientific assessments in providing an accurate perspective on questions asked by policymakers. In climate, the IPCC, if
it did not exist, would have to be invented. If members of Congress wish to tosecure robust answers to questions of climate science, impacts or economics,
they might look to the IPCC.
• However, if the IPCC is not viewed to be legitimate, then Congress could easily
request the US National Academy of Sciences (or other authoritative body) toempanel a high level, unimpeachable assessment process. Such assessments
related to climate have of course been done for decades and the overarchingscientific conclusions have remained consistent.
• We have plenty of knowledge and experience about how to arrive at accurate
assessments of the state of scientific understandings on any topic. It is a choice
whether or not to utilize that knowledge and experience.
• Irrespective of the state of scientific understandings, policy action related to energy policies and improving adaptation to climate variability and change does
not require that everyone believe the same things about climate science or thatall uncertainties be eliminated.12

To avoid any confusion: my views on climate science and policy
Because the climate issue is so deeply politicized, it is necessary to include several
statements to clearly present my views. The following conclusions are taken from mybook The Climate Fix in a section entitled ‘Guidelines for a common sense approach
to climate policy’.13 In that book, I call for a low but rising carbon tax to fund energy
innovation, focused on cleaner, cheaper and more broadly accessible energy technologies. If the world’s economy is to decarbonize, it will be because of advances50

in energy technology, and not because everyone comes to hold the same views ofclimate science.14
Increasing carbon dioxide influences the climate system, perhaps dramaticallyand irreversibly
That human activities have led to changes in the earth system is broadly accepted.
So too is the possibility that such changes could lead to undesirable outcomes in the
future. For those wanting to know more – much more – about aspects of climate
science, the report of Working Group I of the IPCC is an excellent place to start further
investigations, even as aspects of that report continue to be contested.
The climate system is subject to multiple human influences
Carbon dioxide. . . is not the only important human influence. The climate system iscomplex and is still not fully characterized. Even so, many scientists and policy makers
have concluded that dealing with carbon dioxide should be a top policy priority.
Our ability to see the future is limited
There are debates about how the future will play out that simply cannot be resolvedon the timescales of decision making. Efforts to gain clarity about the future may
in fact have the paradoxical consequence of making that future even cloudier. Decisions about climate change will occur in the context of contestation, uncertainties
and ignorance.
Certainty is not forthcoming
As decisions are made about decarbonizing economies and improving adaptation toclimate in the coming years, certainties about the long-term climate future are notforthcoming. UK science adviser John Beddington explains, ‘There is a fundamental
uncertainty about climate change prediction that can’t be changed.’ As Andy Revkinsummarizes his years of covering the climate debate:
What the debate comes down to is not whether changes are coming but whenthey’ll occur – and how severe they’ll be. There is serious scientific disagreement
about such vital questions as how fast and far temperatures, seas, and storm
strength could rise.

Such disagreements will persist for the foreseeable future. Uncertainties are a reality
to be lived with and managed. They are not going away.
51

Stabilizing atmospheric concentrations of carbon dioxide does not stop climatechangeCarbon policy is not a comprehensive climate policy. It is possible that the world
could successfully address accumulating concentrations of carbon dioxide in the atmosphere and still have to deal with a significant issue of human influences on the
climate system. For this reason, among others, Mike Hulme has written that climatechange is a problem to be managed, not solved. 15 Our debates about climate change
would benefit by distinguishing carbon policies from greenhouse gas policies andbroader conceptions of climate policy.

Biography of Roger Pielke Jr.
Roger Pielke, Jr. has been on the faculty of the University of Colorado since 2001.
Currently, he serves as the director of the Sports Governance Center, a new initiative on campus, and faculty affiliate of the Center for Science and Technology Policy
Research. He is a Professor in the Environmental Studies Program and from 2001–
2016 was a Fellow of the Cooperative Institute for Research in Environmental Sciences (CIRES). Roger served several terms as the founding director of the university’s
Center for Science and Technology Policy Research. Roger’s research focuses on science, innovation and politics, which he has explored in many topical areas over recent
decades, including: space policy, natural disasters, energy policy, climate policy andmore recently, in sports governance.
Roger holds degrees in mathematics, public policy and political science, all fromthe University of Colorado. In 2012 Roger was awarded an honorary doctorate from
Linköping University in Sweden and he was also awarded the Public Service Awardof the Geological Society of America. Roger also received the Eduard Brückner Prizein Munich, Germany in 2006 for outstanding achievement in interdisciplinary climate
research. Before joining the faculty of the University of Colorado, from 1993-2001
Roger was a scientist at the National Center for Atmospheric Research. Roger is a
Senior Fellow of the Breakthrough Institute, and has held academic appointments at
Macquarie University in Sydney, Australia, Oxford University and the London Schoolof Economics.
Roger has hundreds of peer-reviewed publications and, for those who consider
such things, he has an H-Index of 51 (Google). He is also author, co-author or co-editorof eight books, including The Honest Broker: Making Sense of Science in Policy and Politics published by Cambridge University Press (2007), The Climate Fix: What Scientists
and Politicians Won’t Tell you About Global Warming (2011, Basic Books), and The Rightful Place of Science: Disasters and Climate Change (CSPO: ASU, 2014). His most recent
book is The Edge: The War Against Cheating and Corruption in the Cutthroat World of
Elite Sports (Roaring Forties Press, 2016).
52

Appendix A: 2016 op-ed on my experiences in climate research
My Unhappy Life as a Climate Heretic 16
My research was attacked by thought police in journalism, activist groups funded by billionaires and even the White House.
Much to my surprise, I showed up in the WikiLeaks releases before the election. In
a 2014 email, a staffer at the Center for American Progress, founded by John Podesta
in 2003, took credit for a campaign to have me eliminated as a writer for Nate Silver’s FiveThirtyEight website. In the email, the editor of the think tank’s climate blog
bragged to one of its billionaire donors, Tom Steyer: ‘I think it’s fair [to] say that, without Climate Progress, Pielke would still be writing on climate change for 538.’
WikiLeaks provides a window into a world I’ve seen up close for decades: the debate over what to do about climate change, and the role of science in that argument.
Although it is too soon to tell how the Trump administration will engage the scientific community, my long experience shows what can happen when politicians andmedia turn against inconvenient research – which we’ve seen under Republican and
Democratic presidents.
I understand why Mr. Podesta – most recently Hillary Clinton’s campaign chairman – wanted to drive me out of the climate-change discussion. When substantively
countering an academic’s research proves difficult, other techniques are needed tobanish it. That is how politics sometimes works, and professors need to understandthis if we want to participate in that arena.
More troubling is the degree to which journalists and other academics joined thecampaign against me. What sort of responsibility do scientists and the media haveto defend the ability to share research, on any subject, that might be inconvenient topolitical interests – even our own?
I believe climate change is real and that human emissions of greenhouse gases
risk justifying action, including a carbon tax. But my research led me to a conclusionthat many climate campaigners find unacceptable: There is scant evidence to indicatethat hurricanes, floods, tornadoes or drought have become more frequent or intensein the US or globally. In fact we are in an era of good fortune when it comes to extreme
weather. This is a topic I’ve studied and published on as much as anyone over two
decades. My conclusion might be wrong, but I think I’ve earned the right to share
this research without risk to my career.
Instead, my research was under constant attack for years by activists, journalists
and politicians. In 2011 writers in the journal Foreign Policy signaled that some accused me of being a ‘climate-change denier.’ I earned the title, the authors explained,by ‘questioning certain graphs presented in IPCC reports.’ That an academic whoraised questions about the Intergovernmental Panel on Climate Change in an areaof his expertise was tarred as a denier reveals the groupthink at work.
53

Yet I was right to question the IPCC’s 2007 report, which included a graph purporting to show that disaster costs were rising due to global temperature increases.
The graph was later revealed to have been based on invented and inaccurate information, as I documented in my book The Climate Fix. The insurance industry scientist Robert-Muir Wood of Risk Management Solutions had smuggled the graph into
the IPCC report. He explained in a public debate with me in London in 2010 that hehad included the graph and misreferenced it because he expected future research toshow a relationship between increasing disaster costs and rising temperatures. Whenhis research was eventually published in 2008, well after the IPCC report, it concluded
the opposite: ‘We find insufficient evidence to claim a statistical relationship between
global temperature increase and normalized catastrophe losses.’ Whoops.
The IPCC never acknowledged the snafu, but subsequent reports got the scienceright: there is not a strong basis for connecting weather disasters with human-caused
climate change.
Yes, storms and other extremes still occur, with devastating human consequences,
but history shows they could be far worse. No Category 3, 4 or 5 hurricane has madelandfall in the US since Hurricane Wilma in 2005, by far the longest such period onrecord. This means that cumulative economic damage from hurricanes over the past
decade is some $70 billion less than the long-term average would lead us to expect,based on my research with colleagues. This is good news, and it should be OK to say
so. Yet in today’s hyper-partisan climate debate, every instance of extreme weather
becomes a political talking point. For a time I called out politicians and reporters whowent beyond what science can support, but some journalists won’t hear of this. In
2011 and 2012, I pointed out on my blog and social media that the lead climate reporter at the New York Times, Justin Gillis, had mischaracterized the relationship ofclimate change and food shortages, and the relationship of climate change and disasters. His reporting wasn’t consistent with most expert views, or the evidence. In response he promptly blocked me from his Twitter feed. Other reporters did the same.
In August this year on Twitter, I criticized poor reporting on the website Mashable
about a supposed coming hurricane apocalypse – including a bad misquote of me
in the cartoon role of climate skeptic. (The misquote was later removed.) The publication’s lead science editor, Andrew Freedman, helpfully explained via Twitter that
this sort of behavior ‘is why you’re on many reporters’ “do not call” lists despite yourexpertise.’
I didn’t know reporters had such lists. But I get it. No one likes being told thathe misreported scientific research, especially on climate change. Some believe thatconnecting extreme weather with greenhouse gases helps to advance the cause ofclimate policy. Plus, bad news gets clicks.
Yet more is going on here than thin-skinned reporters responding petulantly toa vocal professor. In 2015 I was quoted in the Los Angeles Times, by Pulitzer prize54

winning reporter Paige St. John, making the rather obvious point that politicians use
the weather-of-the-moment to make the case for action on climate change, even if
the scientific basis is thin or contested.
Ms. St. John was pilloried by her peers in the media. Shortly thereafter, sheemailed me what she had learned: ‘You should come with a warning label: quoting
Roger Pielke will bring a hailstorm down on your work from the London Guardian,
Mother Jones, and Media Matters.’
Or look at the journalists who helped push me out of FiveThirtyEight. My firstarticle there, in 2014, was based on the consensus of the IPCC and peer-reviewed
research. I pointed out that the global cost of disasters was increasing at a rate slower
than GDP growth, which is very good news. Disasters still occur, but their economic
and human effect is smaller than in the past. It’s not terribly complicated.
That article prompted an intense media campaign to have me fired. Writers at
Slate, Salon, the New Republic, the New York Times, the Guardian and others piled on.
In March of 2014, FiveThirtyEight editor Mike Wilson demoted me from staff writer tofreelancer. A few months later I chose to leave the site after it became clear it wouldn’t
publish me. The mob celebrated. ClimateTruth.org, founded by former Center for
American Progress staffer Brad Johnson, and advised by Penn State’s Michael Mann,called my departure a ‘victory for climate truth.’ The Center for American Progresspromised its donor Mr. Steyer more of the same.
Yet the climate thought police still weren’t done. In 2013 committees in the Houseand Senate invited me to a several hearings to summarize the science on disasters
and climate change. As a professor at a public university, I was happy to do so. My
testimony was strong, and it was well aligned with the conclusions of the IPCC andthe US government’s climate-science program. Those conclusions indicate no overall
increasing trend in hurricanes, floods, tornadoes or droughts – in the US or globally.
In early 2014, not long after I appeared before Congress, President Obama’s science adviser John Holdren testified before the same Senate Environment and Public Works Committee. He was asked about his public statements that appeared tocontradict the scientific consensus on extreme weather events that I had earlier presented. Mr Holdren responded with the all-too-common approach of attacking themessenger, telling the senators incorrectly that my views were ‘not representative of
the mainstream scientific opinion’. Mr. Holdren followed up by posting a strange essay, of nearly 3000 words, on the White House website under the heading, ‘An analysisof statements by Roger Pielke Jr.,’ where it remains today.
I suppose it is a distinction of a sort to be singled out in this manner by the president’s science adviser. Yet Mr Holdren’s screed reads more like a dashed-off blog postfrom the nutty wings of the online climate debate, chock-full of errors and misstatements.
But when the White House puts a target on your back on its website, people no55

tice. Almost a year later Mr Holdren’s missive was the basis for an investigation of me
by Arizona Rep. Raul Grijalva, the ranking Democrat on the House Natural Resources
Committee. Rep. Grijalva explained in a letter to my university’s president that I wasbeing investigated because Mr Holdren had ‘highlighted what he believes were serious misstatements by Prof. Pielke of the scientific consensus on climate change’. He
made the letter public.
The ‘investigation’ turned out to be a farce. In the letter, Rep. Grijalva suggested
that I – and six other academics with apparently heretical views – might be on the payroll of Exxon Mobil (or perhaps the Illuminati, I forget). He asked for records detailingmy research funding, emails and so on. After some well-deserved criticism from theAmerican Meteorological Society and the American Geophysical Union, Rep. Grijalva
deleted the letter from his website. The University of Colorado complied with Rep.
Grijalva’s request and responded that I have never received funding from fossil-fuelcompanies. My heretical views can be traced to research support from the US government.
But the damage to my reputation had been done, and perhaps that was the point.
Studying and engaging on climate change had become decidedly less fun. So I started
researching and teaching other topics and have found the change in direction refreshing. Don’t worry about me: I have tenure and supportive campus leaders andregents. No one is trying to get me fired for my new scholarly pursuits.
But the lesson is that a lone academic is no match for billionaires, well-funded
advocacy groups, the media, Congress and the White House. If academics – in any
subject – are to play a meaningful role in public debate, the country will have to doa better job supporting good-faith researchers, even when their results are unwelcome. This goes for Republicans and Democrats alike, and to the administration of
President-elect Trump.
Academics and the media in particular should support viewpoint diversity insteadof serving as the handmaidens of political expediency by trying to exclude voices ordamage reputations and careers. If academics and the media won’t support open
debate, who will?

56

Notes
1. See https://scholar.google.com/citations?user=WtqpmdIAAAAJ.
2. Holdren JP (2014) ‘Drought and global climate change: An analysis of statements by
Roger Pielke Jr.’ 28 February 2014. (Available at: https://obamawhitehouse.archives.gov/sites/
default/files/microsites/ostp/critique_of_pielke_jr_statements_on_drought.pdf.)
3. Grijalva R (2015) ‘Letter from Congressman Raul Grijalva (D-AZ) to Bruce Benson, President,
University of Colorado, 24 February 2015.’
4. Ibid.
5. Quoted in: http://www.al.com/news/huntsville/index.ssf/2015/02/arizona_congressman_
asking_que.html
6. I am very proud to be associated with the University of Colorado, whose leadership offered unwavering support throughout my experiences, see: http://www.dailycamera.com/
cu-news/ci_30558681/cu-board-shows-support-faculty-students-academic-freedom.
7. https://science.house.gov/sites/republicans.science.house.gov/files/documents/HHRG-115SY-WState-RPielke-20170329.pdf.
8. See http://www.ingsa.org/.
9. https://scholar.google.com/scholar?q=scientific+assessments+policy+politics&btnG=&hl=
en&as_sdt=0%2C6.
10. Sarewitz D and Pielke RA (2007) ‘The neglected heart of science policy: reconciling supplyof and demand for science’. Environmental Science & Policy 10: 5–16.
11. See Chapter 6 of The Climate Fix for details.
12. See Pielke Jr. R (2011) The Climate Fix: What Scientists and Politicians Won’t Tell you About
Global Warming, Basic Books)
13. Chapter 1, pp. 32–34
14. More broadly see: Rayner S and Caine M (2014) The Hartwell Approach to Climate Policy,
Routledge.
15. Hulme M (2009). Why we Disagree about Climate Change: Understanding controversy, inaction and opportunity. Cambridge University Press.
16. https://www.wsj.com/articles/my-unhappy-life-as-a-climate-heretic-1480723518

57

GWPF REPORTS
1Montford
2
Ridley3
Hughes4
McKitrick5
Booker6
Montford
7
Goklany
8
Hughes9
Lilley10 Whitehouse
11 Khandekar
12 Lewis and Crok
13 Lewis and Crok
14 Montford and Shade
15 De Lange and Carter
16 Montford
17 Lewin
18 Goklany
19 Adams
20 Laframboise
21 Constable
22 Lilley
23 Humlum
24 Curry et al.

The Climategate Inquiries
The Shale Gas ShockThe Myth of Green Jobs
What Is Wrong With the IPCC?
The BBC and Climate Change
Nullius in Verba: The Royal Society and Climate Change
Global Warming Policies Might Be Bad for Your Health
Why Is Wind Power So Expensive?
What Is Wrong With Stern?
The Global Warming Standstill
The Global Warming-Extreme Weather Link
Oversensitive
A Sensitive Matter
Climate Control: Brainwashing in Schools
Sea-level Change: Living with Uncertainty
Unintended Consequences of Climate Change Policy
Hubert Lamb and the Transformation of Climate Science
Carbon Dioxide: The Good NewsThe Truth About China
Peer Review: Why Scepticism is Essential
Energy Intensive Users: Climate Policy Casualties£300 Billion: The Cost of the Climate Change Act
The State of the Climate in 2016
Assumptions, Policy Implications and the Scientific Method

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the contested science of global warming, is deeply concerned about thecosts and other implications of many of the policies currently being advocated.
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